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• Novel carbazole and diketopyrrolopyrrole-based molecule (CAR-TzDPP) was synthesized. • A comparative study between the carbazole and triazatruxene endcaps was conducted. • Experimental and theoretical properties (DFT and TD-DFT) were found in good agreement. • Two-dimensional (2D) ambipolar charge transport was observed in CAR-TzDPP thin film. • Triazatruxene-based molecule (TAT-TzDPP) provides 3D unipolar charge transport. In this work, we describe the design and synthesis of a novel soluble conjugated molecule, CAR-TzDPP , consisting of a central diketopyrrolopyrrole core (DPP) connected to carbazole endcaps through thiazole rings. To evaluate its properties, a triazatruxene-based molecule (TAT-TzDPP) was used as a model for comparison. The electrochemical and the in-solution optical properties are in good agreement with those obtained from DFT calculations. However, the thin-film self-assemblies of CAR-TzDPP exhibited distinct differences, forming a more standard crystalline structure including insulating side-chains layers that disallowed side interactions between aromatic rings. This resulted in a reduced charge transport ability to a two-dimensional (2D) ambipolar charge transport in CAR-TzDPP , compared to the nearly isotropic unipolar charge transport in TAT-TzDPP. Despite this, CAR-TzDPP can be considered a viable alternative for device configurations requiring semiconducting pathways aligned in the substrate plane due to its simplified and high yield synthesis route, ease of processing, and reliable charge mobility in OFETs. This research highlights the significance of molecular units in small semiconducting organic molecules, not only in terms of their individual optoelectronic properties but also in terms of their self-assembly capabilities, which ultimately influence their charge transport properties. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • 1,4-bis(4-vinylpyridyl)benzene (bvpb), a double heterostilbene, was synthesized and characterized. • Electrochemical Surface-Enhanced Raman Spectra (SERS) of bvpb put in evidence a resonance process at −1.0 V with 785 nm excitation line. • The study of dynamic relaxation processes by femtosecond Transient Absorption Spectra (TAS) shows a first excited state (S 1) at 607 nm in which a trans–cis rotation of the vinyl bond is involved. • DFT potential energy curve of vinyl torsion predicts a low barrier height between trans- and cis -conformers in S 1 state with a S 1 /S 0 conical intersection corresponding to a twisted vinylpyridyl bond. • The synergy of experimental data, SERS and TAS, and DFT calculations shows bvpb can act as a conformational molecular switch addressed by electric potential under a selected wavelength. The electrochemical surface-enhanced Raman spectra (SERS) of 1,4-bis(4-vinylpyridyl)benzene (bvpb) recorded at different electrode potentials with three excitation wavelengths (785, 532 and 473 nm) point out there exists a resonance process involved at more negative voltage with the 785 nm line, giving two strongly enhanced SERS bands at about 1500 and 1150 cm−1. This result agrees with the VIS-NIR transient absorption spectrum characterized by a strong band at 607 nm and a weaker one at 1163 nm, corresponding to the first singlet (S 1) and triplet (T 1) excited electronic states. The DFT potential energy curve corresponding to the trans – cis (E-Z) isomerization in the S 0 state and in the two lowest S 1 and T 1 excited states, indicates that the S 1 state exhibits a significant lower barrier height than S 0 state, showing also a S 1 /S 0 conical intersection at a structural conformation in which the vinyl double bond twists by 90°. TD-DFT resonance Raman spectra of the planar and twisted conformation in a simple model of surface complex, Ag 2 0-bvpb, yield that the twisted molecule is able to predict the selected enhancement of the two SERS bands. Therefore, bvpb could act as an electroactive conformational molecular switch under a selected wavelength in nanoelectronic devices. [ABSTRACT FROM AUTHOR]

[Display omitted] • MCD and MCPL: the role of A, B and C terms. • Calculation of A and B terms via TD-DFT methods. • Porphyrinoid systems: highly symmetric and non-symmetric cases. • MCD of natural products extracted from plants: experiments and calculations. • MCD in the IR range: MVCD. A historical sketch of the MCD (magnetic circular dichroism) spectroscopy is reported in its experimental and theoretical aspects. MCPL (magnetic circularly polarized luminescence) is also considered. The main studies are presented encompassing porphyrinoid systems, aggregates and materials, as well as simple organic molecules useful for the advancement of the interpretation. The MCD of chiral systems is discussed with special attention to new studies of natural products with potential pharmaceutical valence, including Amaryllidaceae alkaloids and related isocarbostyrils. Finally, the vibrational form of MCD, called MVCD, which is recorded in the IR part of the spectrum is also discussed. A final brief note on perspectives is given. [ABSTRACT FROM AUTHOR]

We present a theoretical investigation of the structural, electronic and optical properties of few layer graphene/TiO 2 composites involving either single or bilayer graphene and the (101) surface of TiO 2 anatase, in view of the importance of carbonaceous materials such as graphene to enhance solar light-driven photocatalytic activity of TiO 2. Calculations have been performed by combining periodic DFT calculations to TD-DFT carried out on finite clusters extracted from the periodic structures and embedded in an array of point charges devised to reproduce the periodic electrostatic environment. Although van der Waals interactions dominate the graphene/TiO 2 interaction, TiO 2 properties are significantly affected by its combination with graphene in the composite materials. In particular, we found that such materials present favorable key features for photocatalysis applications, with high charge carriers mobilities, an increase of the absorption in the visible range together with a red-shift of the photoresponse of TiO 2. These results confirm that graphene can enhance solar light-driven photocatalytic activity of TiO 2 , especially when few layer graphene-based composites are considered. Furthermore, the proposed computational approach appears as a reliable and effective tool to model both the electronic and the optical properties of heterostructures at low computational cost. [Display omitted] • A reliable and effective computational protocol is proposed to model composites. • Gr-based composites offer better properties than TiO 2 for photocatalysis. • Few layer Gr-based composites offer better properties than single layer ones. [ABSTRACT FROM AUTHOR]

This study investigates the optoelectronic and photoluminescence properties of graphene quantum dots (GQDs) conjugated with the Mitoxantrone (MTX) drug, aiming to enhance cancer drug delivery systems. Using DFT and TDDFT numerical simulations, we examined the impact of GQD size and MTX coupling positions (C–C, C–O, and C–N bonds) on the physical behaviour of DSGQDs. Our study confirm that all structures are energetically stable, as evidenced by the absence of negative frequencies in the IR spectra. Besides, C–O conjugated structures are found to be the most chemically stable as it was shown by global reactivity indices results. Functionalization leads to a reduced H–L energy gap, depending on the MTX coupling position and GQD size. Importantly, the optical properties of GQDs remain largely unaffected by conjugation, maintaining their stability as drug carriers. Larger GQD systems retained stable absorption and photoluminescence characteristics within the near-infrared (NIR) range, while smaller systems exhibited a shift from the visible to the NIR range. Notably, the C 48 H 18 + MTX system with C–O bonding demonstrated superior photoluminescence performance confirmed by the small line width results. These results suggest that GQDs conjugated with MTX hold significant potential for targeted cancer therapy, with minimal interaction between the drug and the GQD host, thereby reducing toxicity risks. [ABSTRACT FROM AUTHOR]

• Development of seven new pyranylidene-based organic dyes for DSSC applications. • Impact of the dye anchoring mode (mono- vs di-) on the photovoltaic performances. • Correlation between structural, electronic and photovoltaic properties of the dyes. • Mono-anchoring dye 17a exhibiting the highest power conversion efficiency of 5.23%. Mono- and di-anchoring γ-pyranylidene-based organic dyes featuring D–π–A and D–(π–A) 2 architectures have been engineered as sensitizers for applications in Dye-Sensitized Solar Cells (DSSCs). Their photophysical, electrochemical and photovoltaic properties were further investigated. TD-DFT calculations were performed to rationalize the trends observed in the optical and electrochemical properties of the dyes. The investigation of the photovoltaic performances of this series of new dyes provided structure–property relationships where their Power Conversion Efficiencies (PCE) could be correlated to structural features, such as the length of the π-conjugated spacer, the nature of the substituents on the pyranylidene electron donor moiety and the number of anchoring groups. Dye-Sensitized Solar Cells based on mono-anchoring dyes were more efficient than the corresponding cells based on di-anchoring analogues due to high dye loading. The highest Power Conversion Efficiency of 5.23% was achieved with the mono-anchoring 17a dye containing t -butyl substituent groups on the pyranylidene fragment and with one thienyl π-conjugated spacer. [ABSTRACT FROM AUTHOR]

A Mn(I) tricarbonyl complex with a nitrobenzodiazole fluorophore releases CO via irradiation with light (λ = 490 nm) with a colorimetric as well as fluorometric dual response. We introduce a colorimetric as well as fluorometric dual response CO-releasing molecule as Mn(I) tricarbonyl complex with a nitrobenzoxadiazole (NBD) fluorophore. DFT and TD-DFT studies corroborate that extended conjugation in the principal ligand frame will help to release CO at low energy radiation. A very low toxicity of NBD-CORM was observed against LX-2 and HepaRG® human cell lines. [ABSTRACT FROM AUTHOR]

The one-pot reaction of N,N′ -bis(3-methoxysalicylidene)-1,4-diaminobutane (MeOsalbnH 2), zinc(II) perchlorate, and lanthanide(III) acetate by a molar ratio of 2:2:1 affords a novel heterotrinuclear Zn 2 Ln (Ln: La, Sm, Eu, Tb) complex formulated as [Ln(CH 3 COO) 2 {Zn(MeOsalbn)} 2 ]ClO 4. The La(III) complex exhibits a bright blue fluorescence, while the Sm(III) complex shows a reddish-orange coloured f–f photoluminescence. The one-pot reaction of N,N′ -bis(3-methoxysalicylidene)-1,4-diaminobutane (MeOsalbnH 2), zinc(II) perchlorate, and lanthanide(III) acetate by a molar ratio of 2:2:1 affords a heterotrinuclear Zn 2 Ln (Ln: La, Sm, Eu, Tb) complex formulated as [Ln(CH 3 COO) 2 {Zn(MeOsalbn)} 2 ]ClO 4. In this complex, the central Ln(III) atom is bridged by two {Zn(MeOsalbn)} units and two acetate ligands to form ten-coordination environment. Each Zn(II) atom is coordinated by MeOsalbn2− through the N 2 O 2 site and one oxygen atom from the bridging acetate to afford a five-coordination geometry. In the crystalline state at room temperature, the La(III) complex exhibits a bright blue fluorescence, while the Sm(III) complex shows a reddish-orange colored f–f photoluminescence via an energy transfer from the T 1 state localized on the {Zn(MeOsalbn)} units to the acceptor level of the central Sm(III) ion. The results of TD-DFT calculations show that the lowest excited singlet state or triplet state involved in photoluminescence of the La(III) or Sm(III) complex has some intramolecular charge-transfer (CT) character from the phenoxo or methoxy groups to the imino groups in the coordinated MeOsalbn2− moieties. [ABSTRACT FROM AUTHOR]

In the present study, we use a dual approach comprising of experimental and computational techniques to report the syntheses, characterizations (1H NMR, 13C NMR, FT-IR, UV–visible spectroscopy and X-ray structure determination) and theoretically evaluated the third order NLO response properties of the new organic compounds; 1-((E)-(2-methoxy-4-nitrophenylimino)methyl)naphthalen-2-ol hydrate (HL1), (E)- N -(ethoxy(2,3-dichlorophenyl)methyl))-2-methoxy-4-nitrobenzenamine(L2) and copper(II) complex [Cu(L3)(py)] of (E)- N '-(3,5-dichloro-2-hydroxybenzylidene)benzohydrazide(H 2 L3). The HL1 and L2 were crystallized in the triclinic system of the space group P-1 with two molecules in the unit cell, whereas complex [Cu(L3)(py)] was crystallized in the monoclinic system in the space groups P2 1 / c with eight molecules in the unit cell. The thermal properties (DSC and TG-DTG analysis) of these compounds were also investigated. State of the art quantum computational methods are performed at molecular and bulk levels to get structure-property relationships from molecule to materials. For HL1, L2 and complex [Cu(L3)(py)], their isotropic (anisotropic) values are found to be 55.46 × 10−24 esu (71.69 × 10−24 esu), 44.67 × 10−24 esu (26.92 × 10−24 esu) and 60.73 × 10−24 esu (69.71 × 10−24 esu), respectively. The differences in isotropic and anisotropic values are 16.23 × 10−24 esu, 17.75 × 10−24 esu and 9.00 × 10−24 esu, respectively. The NLO response properties including third-order polarizability (γ) are calculated using density functional theory (DFT) methods. The calculated γ amplitudes for the synthesized HL1, L2 and complex [Cu(L3)(py)] are found to be 801.54 × 10−36, 77.81 × 10−36 and 311.17 × 10−36 esu, respectively. These γ amplitudes of HL1, L2 and complex [Cu(L3)(py)] are about 44, 4 and 17 times larger than that of standard para -nitroaniline (PNA, a prototype NLO molecule), respectively, which show the potential of these compounds as efficient NLO materials. Their electronic parameters and NLO properties were also evaluated using TD-DFT calculations. The HL1, L2 and complex [Cu(L3)(py)] showed maximum absorptions with oscillator strengths of 0.749, 0.393 and 0.368 at 2.751 3.476 and 3.214 eV, respectively. Image 1 • Syntheses and characterizations of new organic compounds and Cu(II) complex. • The electronic structures were studied by X-ray crystallography. • The DFT calculations showed the good NLO response properties. • The FMOs and MEPs were used to reveal structure-property relationship. • NMR, FT-IR and UV–Vis spectral analysis were carried out. [ABSTRACT FROM AUTHOR]

• Computational intelligence and/or augmented intelligence is used to guide the design for structure-property relationship for organic photovoltaic (OPV) cells. • The donor – π spacer –acceptor architecture provides significant potential to design new dyes using variety of conjugated π-spacer building blocks of OPV cells. • A potential to build a database of π-spacers, for DCPA–π- spacer–PMID dye sensitizers in the search for high performance organic DSSCs. The same strategy can be applied to search for donors and acceptors of donor – π spacer –acceptor dyes. • Modulation of π-spacers can lead to machine learning and artificial intelligence to predict composition, structure and properties once sufficient information is produced. Organic photovoltaic (OPV) solar cells recently achieved a reported efficiency as high as 17.3%. In this study we explore new avenues of shifting the light absorber through rational design of the π-spacers in the Donor–π-spacer–Acceptor dyes. That is, to construct high performing new dyes with fixed donor (DCPA) and acceptor (PMID) from appropriate π-building units of fluorene, EDOT and thiophene. These three π-units form various combinations of the π-conjugate spacers for new dyes. We focus on the development of the relationship between the three building units of π-spacers to construct new DCPA–π-spacer–PMID dyes and their UV–vis spectra in tetrahydrofuran (THF) solution. The latter (i.e., UV–vis spectra) are calculated using quantum mechanical time dependent density functional theory (TD-DFT) methods. This set of nine new organic dyes has been employed to develop augmented intelligence (AI). We discovered that repeating the fluorene (πO) unit alone in the π-spacer, such as OP100, OP200 and OP300 dyes, will lead to hyperchromic enhancement of the donor spectral band in the UV region of ca. 300 nm, with limited impact on the major spectral band at 500 nm which is stemmed from the acceptor (PMID). To maximize the UV–vis absorption, more efficient π-spacers for this class of dyes are constructed from mixtures of the fluorene (πO) and EDOT (πP) units, such as πO-πP-πO (OP210) or as πO-πP-πO-πP (OP220). The information obtained is useful to elucidate new dyes with desired properties with appropriate UV–vis spectra for future machine learning (ML). [ABSTRACT FROM AUTHOR]

Abstract In this paper, we report the synthesis of new unsymmetrical azines Schiff bases. These compounds were prepared by condensation of hydrazine with different aldehydes and ketones to give (E) -2-hydroxynaphthalene-1-carbaldehyde [(1E) -2-thienylmethylene] hydrazone compound (I) and (Z) - 2 - [(E) -1- (2-hydroxyphenyl) ethylidenehydrazin-1-ylidene] -1,2-diphenylethanone compound (II). The method adopted consists in reacting the two different carbonyl compounds simultaneously in one step in a stepwise manner reported which is practical and cost-effective. The reaction with a minor modification in operating conditions proceeded efficiently and with excellent performance. The structure of each of the two compounds (I) and (II) was determined by the X-ray diffraction technique performed on single crystals. The asymmetric unity of the two molecules consists of one asymmetry-independent molecule. In addition, hydrogen bonds C H ... π are observed in the compound (II). We then present a detailed DFT study based on B3LYP/6-31G (d, p) geometric structures of compounds (I); (II) and another compound (III) also another asymmetric azine (Z) -2 - [(E) -2-benzylidenehydrazine-1-ylidene] -1,2-diphenylethanone whose crystal structure is reported. The fundamental vibration wave numbers are calculated and a good agreement between the observed and calculated wave numbers is obtained. The study was extended to the HOMO-LUMO analysis to calculate the energy gap. The calculated HOMO and LUMO energy reveals that the charge is transferred into the molecule. Highlights • The synthesis of new unsymmetrical Schiff bases is reported. • Three new hydrazine are characterized through UV–Vis, FT-IR, and X-ray analysis. • Calculated UV–vis absorption in excellent agreement with the experimental data. [ABSTRACT FROM AUTHOR]

Abstract Condensation reaction of 6-formylvisnagin (1) with 1-amino-4,6-dimethyl-2-oxo-1,2-dihydropyridine-3-carbonitrile (2) afforded the novel 1-{[(4-methoxy-5-oxo-5 H -furo[3,2- g ]chromen-6-yl)methylidene]amino}-4,6-dimethyl-2-oxo-1,2-dihydro-pyridine-3-carbonitrile (MFCMP). The structure of this compound was deduced on the basis of it's corrected analytical and various spectral data. The parameters of the structure were extracted by using the DFT/B3LYP/ 6-311G (d,p) premise set. Besides, TD-DFT estimations were used for the interpretation of the electronic absorption. The experimental optical absorption results indicated an allowed direct transition at 2.29 eV, corresponding to the optical band gap of the synthesized compound film, as well as Urbach tail width with the energy of 0.51eV. The electrical characteristics of the heterojunction based MFCMP were accomplished in dark and under various intensity levels of illuminations. Both values of the photocurrent and photosensitivity were found to increase with increasing illumination intensity which gives confirmation for the applicability of the studied heterojunction for the optoelectronic devices. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Synthesis of D-π-A chromophores with quinoxaline core in the π-bridge. • High thermal stability and first hyperpolarizability. • High values of NLO coefficients. Abstract Two chromophores with π-deficient quinoxaline (Q) core in the π-electron bridge together with dibutylaniline (DBA) donor moiety and tricyanofuranyl (TCF) or dicyanovinyl (DCV) acceptor moieties have been synthesized to investigate their macroscopic nonlinear optical (NLO) activity in guest-host materials. A distinctive feature of the 7-DBA-VQ Ph V-TCF chromophore is predominance of negative solvatochromism over the positive one, which is quite rarely met for the chromophores manifesting inverse solvatochromic behavior as well as the blue shift of the absorption maximum compared to the chromophore FTC with divinylthiophene π-bridge. Introduction of quinoxaline moiety in the conjugated bridge promotes the increase of thermal stability: T d of both compounds is higher than 225 °C. Density functional theory was used to calculate the chromophores first hyperpolarizability (β). Quadratic NLO response characterized by d 33 coefficient was measured by SHG technique for thin guest-host polymer films. The influence of chromophore content on the NLO coefficient of 7-DBA-VQ Ph V-TCF/PMMA film has been investigated and the d 33 value of this film reaches 108 pm/V at 25 wt% load. The poled film 7-DBA-VQ Ph -DCV/PMMA shows twice smaller d 33 values (30 pm/V) at the same chromophore load (20 wt%). [ABSTRACT FROM AUTHOR]

Abstract The optical limiting (OL) properties of 3,5-di- p -benzyloxystyrylBODIPY dyes that contain both protons and bromine atoms at the 2,6-positions have been investigated by using the Z-scan technique at 532 nm on the nanosecond timescale. There is relatively weak absorbance at 532 nm under ambient light conditions, because the incorporation of p -benzyloxystyryl groups at the 3,5-positions results in a ca. 140 nm red shift of the main BODIPY spectral band to the 640–670 nm range. Reverse saturable absorbance (RSA) profiles that are consistent with an excited state absorption (ESA) mechanism involving the T 1 and/or S 1 states are observed in CH 2 Cl 2 solution. Second order hyperpolarizability values of ca. 8 × 10−30 esu are obtained and this demonstrates that the dyes are potentially suitable for use in OL applications at 532 nm. There is a slight enhancement of the OL properties upon bromination, due to increased intersystem crossing to the triplet manifold, but the enhancement of the OL properties is less significant than has been observed with metal phthalocyanine complexes. Highlights • The optical limiting properties of two novel 3,5-distyryl BODIPY dyes are analyzed. • The effect of bromination at the 2,6-positions on the BODIPY core is investigated. • Bromination is found to enhance the second-order hyperpolarizability value. • Halogenation may be a useful structural modification strategy for this application. [ABSTRACT FROM AUTHOR]

Abstract A series of five new fluorescent dyes of naphthalene based 2-pyrazoline derivatives with different electron donating/withdrawing substituents at para position of N1 phenyl group were synthesized and their structures were elucidated by spectroscopic methods and elemental analysis. The absorption and fluorescence properties of the new fluorescent dyes were studied using steady state and time-resolved techniques. Comparison of the spectroscopic properties of the five derivatives with different electron donating and withdrawing groups in dichloromethane revealed little influence of substituents on absorption spectra. However, the fluorescence spectra of these molecules have been greatly affected. Time-resolved measurements were performed and two lifetimes were obtained. The mean lifetimes for the pyrazolines containing donor groups were found to be higher than those with withdrawing groups. For all compounds, the ground state geometry was optimized in gaseous phase and in dichloromethane using density functional theory (DFT) at B3LYP/6–31G(d) level of theory to obtain frontier molecular orbitals, energy gap and dipole moments. The optimized excited state geometries using TD-DFT at the same level of theory was used to predict absorption and emission energies. HOMO and LUMO energies were also calculated using cyclic voltammetry and were found to have good agreement with those obtained by theoretical calculations. The reorganizational energies calculated theoretically suggest that these compounds can act as good electron and hole transport materials. [ABSTRACT FROM AUTHOR]

• 2-Carbethoxy-3-oxo-1,2,3,4-tetrahydroquinoxaline (CTQ) was synthesized using a condensation reaction between o-phenylenediamine and diethylbromomalonate under regulated conditions. • CTQ compound was used as a powerful adsorbent in the elimination of harmful malachite green (MG) dye from wastewater using the spectrophotometer technique. • By applying Hartree-Fock (HF) and density functional theory (DFT-B3LYP) with 6-31G(d,p) as the basis, the optimized geometries, vibrational wavenumbers, intensities of vibrational bands, and various atomic charges of 9VC have been investigated. • Various factors affecting the removal of this toxic dye were examined. • To show the equilibrium of the adsorption, Freundlich and Langmuir isotherm models were utilized. 2-Carbethoxy-3-oxo-1,2,3,4-tetrahydroquinoxaline (CTQ) was synthesized using a condensation reaction between o-phenylenediamine and diethylbromomalonate under regulated conditions. CTQ compound was used as a powerful adsorbent in the elimination of harmful malachite green (MG) dye from wastewater using the spectrophotometer technique. By applying Hartree-Fock (HF) and density functional theory (DFT-B3LYP) with 6-31G(d,p) as the basis, the optimized geometries, vibrational wavenumbers, intensities of vibrational bands, and various atomic charges of 9VC have been investigated. The basic vibrational modes measured experimentally are analyzed and compared to theoretical predictions. Density functional theory (DFT) was used to examine the geometry, electronic structure, polarizability, and hyperpolarizability of the hybrid blend organic dye (CTQ+MG)HB, which contains π-conjugated tetrahydroquinoxaline unit with an electron donor-acceptor moiety, and time-dependent DFT (TD-DFT) with several hybrid functionals were used to examine the electronic absorption spectrum. Various factors affecting the removal of this toxic dye like adsorbent dose, contact time, initial dye concentration, and dye solution temperature were examined. To show the equilibrium of the adsorption, Freundlich and Langmuir isotherm models were utilized. Freundlich and Langmuir's equations' correlation coefficient values were found to be in perfect agreement. The transfer of MG to quinoxaline is regulated by a pseudo-second-order procedure. The adsorption approach was a spontaneous and exothermic type. A suitable reaction mechanism has also been described and explored in this study along with an analysis of the thermodynamic parameters. [Display omitted] [ABSTRACT FROM AUTHOR]

We report the synthesis and characterisation of known and novel analogues of β-carboline, a naturally occurring alkaloid. Striving to induce changes in the optical properties of carboline, we first focus on substitutions at position 1 before exploring other positions. The β-carbolines were synthesized using, on the one hand, post-synthetic functionalization of biosourced products and, on the other hand, total synthesis of the desired compounds. Our strategy mainly relies on the well-known Pictet-Spengler reaction, followed by aromatization using different techniques. Post functionalization were performed by Knoevenagel condensation or pallado-catalyzed cross-coupling. The measured UV–visible and fluorescence spectra show unexpected results with large shifts obtained when changing a few substituents only. For instance, the replacement of the aryl by a styryl substituent induces a bathochromic shift as large as 70 nm. This allowed controlling the position of the emission on a broad range (from 370 to 650 nm). Additionally, protonation of the compounds leads to profound changes in the spectroscopic properties. We indeed observe for some compounds a bathochromic shift in the emission as large as 200 nm upon protonation. The main experimental results are rationalized using theoretical calculations. • Bioinspired fluorophores based on carboline backbones have been synthesized. • Some synthesis started from biosourced derivatives. • Structure-properties relationships have been achieved experimentally and theoretically to rationalize the photophysics. • Emission properties can be modulated by the susbtituents and by protonation of the pyridine. [ABSTRACT FROM AUTHOR]

Abstract New series of polymethine cyanine dyes with different length of π-chain have been synthesized and characterized. These new dyes are based on D-π-A architecture with long π-electron systems. The UV–vis/emission spectral studies showed that the dyes are absorbed in the region of λ max (485–570) nm and emitted at (540–600) nm. This makes these dyes favorable for the detection of biological and chemical analytes. Their electron cloud delocalization in HOMO/LUMO levels were studied by DFT using Gaussian 09 software. DFT results reveal that the dyes showed effective charge separation in its molecular orbitals levels, which reflected in its ICT behavior. Time-dependent density functional theory (TD-DFT) were applied to theoretically explored the first excitation energy (E 0-0) of these dyes which in high compatibility with experimental results with an accuracy of 0.1–0.3 eV. This approach has been successfully applied to describe the great effect of π-conjugation length and substituents of chromophore on the variations of maximum absorption and excitation energy of the dyes. Graphical abstract Image 1 Highlights • New polymethine cyanine dyes with low melting point designed and synthesized. • These dyes could be used as fluorescent probes in various biochemical methods. • Influence the length of π-conjugation on (E 0-0) confirmed by TD-DFT calculations. • Computed HOMO-LUMO using CAM-B3LYP/SSD basis set with an accuracy of 0.1–0.3 eV. • The opportunity of these dyes to be used as an indicator in analytical chemistry. [ABSTRACT FROM AUTHOR]

Abstract A colorimetric and fluorescent chemosensor (chemosensor 2) for the detection of cyanide anions in aqueous solution has been designed and synthesized in high yield. The sensing mechanism of the chemosensor was verified via UV–vis, fluorimetric, and NMR titrations, and was theoretically explained using DFT and TD-DFT calculations. The chemosensor could optically discriminate the presence of fluoride ions over other anions by a color change from yellow to red with an enhancement of pink fluorescence in DMSO. However, it showed strong green fluorescence when CN− was added to a mixture of DMSO/water (6:4 v/v). Thus, the chemosensor can be employed in selective detecting of CN− besides other interference anions (F−, AcO− and H 2 PO 4 −) in aqueous solution. Moreover, 2 can be used to detect CN− at a concentration as low as 0.32 μM, which is lower than the WHO guideline (2.7 μM) for cyanide. A low quantity of CN− (1.08 μM) can be detected and quantified using the prepared chemosensor. Moreover, the UV–vis and fluorescence spectroscopy studies of the interactions between 2 and dublex DNA revealed intercalative binding of calf thymus DNA to the chemosensor. Graphical abstract Image 1 Highlights • A novel and synthetically facile Coumarin-thiophene-derived Schiff base were synthesized. • The chemosensor is sensitive and selective towards cyanide ions in aqueous solution. • It can be employed detecting of cyanide ions in tap drinking water. • Di-deprotonation sensing mechanism via ICT of the sensor were explained by experimental studies and theoretical methods. • UV–vis and fluorescence spectroscopy studies showed that the chemosensor bind dublex DNA. [ABSTRACT FROM AUTHOR]

Two novel chromophores with dibutylaniline donor moiety, 3,7-(di)vinylquinoxalinone π-electron bridge and tricyanofuranyl or dicyanovinyl acceptor moieties are synthesized and their properties were systematically investigated. Atomistic modeling of PMMA-based composites with the developed chromophores as guests is performed and nonlinear optical activity is studied for the first time. Atomistic modeling performed in the amorphous cell has shown that chromophore content 20 wt% may be considered most favorable for achievement of optimal d 33 values for 7-DBA-VQ on V-TCF/PMMA material. Various non-covalent interactions both between chromophores and polymer matrix and chromophores inter se were revealed in the course of modeling; these interactions could contribute to the relaxation stability of orientational order and thus quadratic NLO response. Composite material 7-DBA-VQ on V-TCF/PMMA is characterized by nonlinear-optical coefficient, d 33 , values of 97, 111 and 47 pm/V at chromophore content of 10, 20 and 30 wt%, respectively. Thus chromophore content 20 wt% provides maximal value of NLO coefficient, what is in agreement with the obtained theoretical data. The d 33 value for 7-DBA-VQ on V-DCV/PMMA is 2.5 times smaller than that for 7-DBA-VQ on V-TCF/PMMA at the same chromophore load (20 wt%). [ABSTRACT FROM AUTHOR]

Four chromophores belonging to a new class of push-pull chromophores with divinylphenylquinoxaline moieties have been designed and synthesized. The structure-property relationship was systematically investigated; the effect of the conformation on the value of chromophores first hyperpolarizability is found to be inessential. Quinoxaline-based chromophore with TCF acceptor and 7-dimethylanilinovinyl moiety displays the combination of favorable characteristics: the high value of the first hyperpolarizability, the small HOMO-LUMO energy gap, the blue shift of the absorption maximum relative to the chromophores with other divinylhetaryl or polyene π-bridges and ultrahigh thermal stability. This chromophore may be considered as a perfect candidate for the development of effective electro-optic materials. [ABSTRACT FROM AUTHOR]

For the first time the nonlinear optical (NLO) activity of indolizine-based push-pull chromophores with different acceptor moieties was studied and compared. All the chromophores demonstrate strong absorption band in the visible (orange-red) part of the spectrum, with ε of ca. 10 5 L∙cm −1 ∙M −1 notably dependent on medium polarity. Replacement of Ph-TCF acceptor by Hex-TCP one results in twofold increase of the first hyperpolarizability value. Energy gaps estimated by electrochemical methods decrease in the series ΔE 1a,b >ΔE 3a,b >ΔE 2a,b for compounds with Ph-TCF, DCM and Hex-TCP acceptors, respectively, good agreement with DFT estimations is obtained. The nonlinear optical coefficient for poled PMMA-based films, containing 20 wt% of isomeric indolizine chromophores with weaker dicyanomethylene (DCM) acceptor and with π- bridge expanded by isophorone moiety, achieves 36 pm/V, thus exceeding those for materials containing chromophores with stronger Ph-TCF or Hex-TCP acceptors and with short vinylene π-bridge. [ABSTRACT FROM AUTHOR]

The question investigated in this study is which functional/s of the twelve tested density functionals in combination with PCM-LR can reproduce the absorption and emission spectra of DFTP dye in three solvents with different polarity. DFTP is an abbreviation of 1-(2,5-dimethylfuran-3-yl)-3-(2,4,5-trimethoxyphenyl)prop-2-en-1-one, and it is with D-π-A structure. The twelve functionals range from standard pure to hybrid and long-range corrected functionals. The simulation of the experimental data included the ability to reproduce the maximum wavelength/transition energy of the absorption and emission spectra as well as the Stokes shift in CCL 4 , ethanol and DMSO solvents. The geometrical parameters and dipole moments of the ground and first excited singlet states were compared and discussed too. The PBE0 functional appears as the best one in reproducing the absorption, emission and Stokes shifts. [ABSTRACT FROM AUTHOR]

Hybrid gold nanoparticles covalently coated with 5,10,15- p -(ω-methoxy polyethyleneoxyphenyl)-20- p -(hydroxyphenyl) porphyrin molecules, having about 16 repetitive units in each of its poly(oxyethylene) branches, were synthesized and characterized by UV–vis, fluorescence, dynamic light scattering (DLS), transmission electron microscopy (TEM) and scanning transmission electron microscopy (STEM) measurements. Their [H 3 O + ] optical sensing behavior was also studied and compared to that of the similar water-soluble star polymer 5,10,15,20-tetrakis p -[ω-methoxypoly(ethyleneoxy)]phenylporphyrin. Changing the pH of a solution, the UV–vis spectra of the PEGylate porphyrin gold nanoparticles conjugates showed the gradual disappearance of the Soret band at 424 nm and the progressive increase of a new band at 451 nm. Upon acidic titration, also the fluorescence spectra showed a gradual disappearing of the fluorescence at 654 nm. Moreover, an unusual B-Band red-shift and a decreasing of porphyrin core basicity were observed for this porphyrin bonded to the gold nanoparticle surfaces. To rationalize these phenomena an in silico TD-DFT calculation study was then conducted. For its properties, this new system: can be used in both aqueous and organic media; by a simple treatment of the solution at 80 °C under N 2 gas stream the starting Soret signals can be recovered; the nanoparticles can be eventually removed from the solution by centrifugation. [ABSTRACT FROM AUTHOR]

In this work, we studied the complexation mode between copper(II) ion and the specific ligand investigated as carriers of metals though biological membranes, diethyldithiocarbamate (Et 2 DTC). It is important to understand how this occurs because it is an important intracellular chelator with potential therapeutic applications. Theoretical and experimental UV visible studies were performed to investigate the complexation mode between copper and the ligand. Electrochemical studies were also performed to complement the spectroscopic analyses. According to the theoretical calculations, using TD-DFT (Time dependent density functional theory), with B3LYP functional and DGDVZP basis set, implemented in Gaussian 03 package, it was observed that the formation of the complex [Cu(Et 2 DTC) 2 ] is favorable with higher electron density over the sulfur atoms of the ligand. UV/Vis spectra have a charge transfer band at 450 nm, with the DMSO-d6 band shift from 800 to 650 nm. The electrochemical experiments showed the formation of a new redox process, referring to the complex, where the reduction peak potential of copper is displaced to less positive region. Therefore, the results obtained from this study give important insights on possible mechanisms involved in several biological processes related to the studied system. [ABSTRACT FROM AUTHOR]

Two series of isomeric indolizine-based chromophores with isophorone rings as a π-bridge have been synthesized and systematically investigated. The chromophores have a high thermal stability: the decomposition temperature is above 238 °C. For isomers with 1-methyl-2-phenylindolizin-3-yl (MPI-3) donor group higher values of β are predicted in comparison with those having 3-methyl-2-phenylindolizin-1-yl (MPI-1) donor group. This is in good agreement with the experimental and theoretical values of the HOMO-LUMO energy gap. Indolizine-based chromophores with barbituric acceptor and isophorone moieties in the π-bridge demonstrate the combination of good characteristics. [ABSTRACT FROM AUTHOR]

Density functional theory (DFT) and time-dependent density functional theory (TD-DFT) approaches were applied to explore the effect of central transition metals and the dye/TiO 2 interface on dye-sensitized solar cell (DSSC) performance and supply a promising way to estimate and screen possible candidates for DSSC applications. The interaction properties, bonding characteristics, sensitized mechanisms, charge transfer, frontier molecular orbitals, energy gap, partial densities of states (PDOS), non-covalent interactions (NCI), and electronic absorption spectra were examined and analyzed to provide the photovoltaic characteristics of Sc, Cu, and Ti tetrasulfonic acid phthalocyanine sensitizer@TiO 2 interface in both gas phase and polar solvent as acetonitrile. The interfacial of TiPc-(SO 3 H) 4 with TiO 2 , which facilitates the driving force for the electron injection of photosensitizers ( Δ G inj ) , increases the charge separation, open-circuit voltage (V oc), and high light-harvesting efficiency (LHE) values. However, minimize the charge recombination, lifetime of the excited state (τ), regeneration driving force ( Δ G reg). Our results reveal that TiPc-(SO 3 H) 4 @TiO 2 is superior to those of ScPc-(SO 3 H) 4 , CuPc-(SO 3 H) 4 , TiPc-(SO 3 H) 4 and Pc-(SO 3 H) 4 /TiO 2 , indicating the novel TiPc-(SO 3 H) 4 @TiO 2 interface could be promising candidates for DSSC photovoltaic devices performance. In addition, the static mean polarizability and first hyperpolarizability of all six dyes elucidated that the TiPc-(SO 3 H) 4 @TiO 2 interface can be regarded as a potential performer in non-linear optical (NLO) properties. These theoretical identifications may provide novel perspectives and instructions for future experimental researchers to promote the synthesis and application of TiPc-(SO 3 H) 4 @TiO 2 interfaces to improve the photo-to-current conversion efficiency. [Display omitted] • The studied dyes showed a good performance of Δ G inj , V OC , J SC and dye regeneration. • TiPc-(SO 3 H) 4 /TiO 2 with the longest τ showed the most prominent charge transfer efficiency. • The reported dye interfaces illustrated red-shift absorption spectra and high IPCE. • TiPc-(SO 3 H) 4 /TiO 2 is expected as the promising candidates with a superior performance. • The solvent effects were investigated for all the studied dyes. [ABSTRACT FROM AUTHOR]

Impact of π-deficient heterocyclic core (A′) in conjugated bridge of D-π-A′-π-A chromophores (D = N,N- dihexylaniline, A = tricyanofuran derivative) on optical and thermal properties has been investigated. Three new chromophores with vinyl-hetaryl-vinyl bridges containing π-deficient benzoazine moiety (quinoxaline, quinoxalinone and quinoline) have been synthesized along with new chromophores with vinyl-thiophene-vinyl bridge containing π-excessive heterocycle and short vinylene bridge, and their properties are compared to reveal the role of π-deficient hetaryl moiety. Their linear optical properties were systematically investigated by UV–Vis spectroscopy and molecular nonlinear optical (NLO) characteristics were predicted by DFT calculations. As the aromaticity of the heterocycle in the bridge increases, a hypochromicity and hypsochromic shift of the absorption maximum manifest themselves in the UV–Vis spectra, the origin of electron transitions was studied by TD-DFT with CAM-B3LYP and PBE0 density functionals. The calculated first hyperpolarizability, β tot , for A′ = quinoxaline, quinoline and thiophene, was shown to be almost independent on the type of the π-bridge core, being in a narrow interval 800–831⋅10−30 esu, while for A′ = quinoxalinone β tot is essentially higher (996⋅10−30 esu). All chromophores exhibit good thermal stability (T d > 192 °C). Thin films of composite polymer materials with PMMA matrix and studied chromophores as guests as well as of some molecular glasses were spin-cast and corona-poled, and their quadratic NLO activity was measured by two different techniques. For materials with guest chromophores containing quinoxalinone, quinoxaline and thiophene moieties in the bridges NLO coefficients d 33 were found to be rather close and reached 76 pm/V, what is almost 3 times higher than that for polymer film with quinoline-based chromophore. Rather high values of NLO coefficients for molecular glasses based on chromophores with quinoline, thiophene and quinoxalinone cores were obtained: 52, 124 and 132 pm/V, respectively, which notably exceed the values for composite materials with these chromophores as guests. [Display omitted] • First representative of a new class of NLO chromophores with divinylquinoline bridge was synthesized. • UV–vis spectra of quino(xa)line chromophores have high-intensity line in higher energy region. • Polymer composites with quinoxalin(on)e and thiophene chromophores have close d 33 values. • Quinoxalinone chromophore molecular glass exhibits high NLO coefficient value of 132 p.m./V. [ABSTRACT FROM AUTHOR]

Novel 6 H -cyclohepta[ c ]furan derivatives possessing aryl groups on 1,3-position were synthesized, and their photophysical behavior were investigated. 1,3-Diphenyl-5,7-difomyl derivative showed solvatochromism. As the electron donating ability at 1,3-positions and the electron withdrawing ability at 5,7-positions increased, the absorption and emission wavelengths were bathochromically shifted. Theoretical calculations revealed that their photophysical behaviors are reproduced. [ABSTRACT FROM AUTHOR]

As part of a study of pyrrole hydrazone, we have investigated quantum chemical calculations, molecular geometry, relative energy, vibrational properties and antimycobacterial/antimicrobial activity of pyrrole-2-carboxaldehyde isonicotinyl hydrazone (PCINH), by applying the density functional theory (DFT) and Hartree Fock (HF). Good reproduction of experimental values is obtained and with small percentage error in majority of the cases in comparison to theoretical result (DFT). The experimental FT-IR and Raman wavenumbers were compared with the respective theoretical values obtained from DFT calculations and found to agree well. In crystal structure studies the hydrated PCINH ( syn - syn conformer) shows different conformation than from anhydrous form ( syn - anti conformer). The rotational barrier between syn - syn and syn - anti conformers of PCINH is 12.7 kcal/mol in the gas phase. In this work, use of FT-IR, FT-Raman, 1 H NMR, 13 C NMR and UV–Vis spectroscopies has been made for full characterization of PCINH. A detailed interpretation of the vibrational spectrum was carried out with the aid of normal coordinate analysis using single scaling factor. Our results support the hydrogen bonding pattern proposed by reported crystalline structure. The calculated nature of electronic transitions within molecule found to be π → π*. The electronic descriptors study indicates that PCINH can be used as robust synthon for synthesis of new heterocyclic compounds. The first static hyperpolarizability (β 0 ) of PCINH is calculated as 33.89 × 10 − 30 esu , (gas phase); 68.79 × 10 − 30 (CHCl 3 ), esu; 76.76 × 10 − 30 esu (CH 2 Cl 2 ), 85.16 × 10 − 30 esu (DMSO). The solvent induced effects on the first static hyperpolarizability were studied and found to increase as dielectric constants of the solvents increases. Investigated molecule shows better NLO value than Para nitroaniline (PNA). The compound PCINH shows good antifungal and antibacterial activity against Aspergillus niger and gram-positive bacteria Bacillus subtilis , respectively. The compound also shows good antituberculosis activity against Mycobacterium tuberculosis H37Rv using the microplate alamar blue assay (MABA). [ABSTRACT FROM AUTHOR]

New 2,3-naphthalimide derivatives bearing phenyl substituents on the naphthalene skeleton were synthesized, and their UV/vis absorption and fluorescence properties were investigated. The fluorescence intensity of the short wavelength emission was strengthened as the increase in the number of the phenyl groups on the naphthalene skeleton. [ABSTRACT FROM AUTHOR]

With 4-fluorostyrene as the starting material, symmetric/asymmetric fluorine-containing aza-difluoroboradiaza- s -indacenes (aza-BODIPYs) 3–6 at 1/7-position were successfully prepared. NaN 3 undertook nucleophilic aromatic substitution via replacement of F atoms of 4 to form the N 3 /NH 2 -containing aza-BODIPYs 9 and 10 . The solid-state structure of aza-BODIPY 4 was confirmed by single crystal X-ray analysis, the F-C Ph bond distance of which was found to be shorter than those of the reported fluoride. These aza-BODIPYs absorb and emit in the NIR region. Surprisingly, although the withdrawing group was introduced at 1/7 positions of 3 – 6 , the effect of the fluorine atoms to the photophysical properties is trifling. However, 9 and 10 with N 3 / NH 2 groups resulted in a remarkable bathochromic shift. Aza-BODIPY 10 could be also used as a turn-on fluorescent probe for pH value. Moreover, the main photophysical data are well supported and explained by cLR-PCM(CHCl 3 )-M06-2X/6-311 + G(2d,p)/SOS-CIS(D) calculations. [ABSTRACT FROM AUTHOR]

[Display omitted] • The drug-loading capacity for anticancer 5FU drug at Fe 6 @B 40 was investigated. • (5FU) 6 @[Fe 6 @B 40 ] has a high capacity for delivering of multiple 5FU molecules. • The 5FU can be separated from Fe 4 @B 40 and Fe 6 @B 40 at ambient temperature. • The solvent effects of 5FU at M@B 40 nanocages (M = Na, Mg and Fe) were examined. • NBO, PDOS, NCI, AIM, ELF and NLO of have been analysed. The potential of exohedral metalloborospherene (Na@B 40 , Mg@B 40 , Fe@B 40 , Fe 4 @B 40 and Fe 6 @B 40) for delivery of anti-cancer 5-fluorouracil (5FU) have been investigated using DFT calculations. The NBO analysis, statistical thermodynamics, PDOS characteristics, NCI and QTAIM descriptors of these systems were investigated to analyze the interaction process. UV–visible electronic absorption spectra in the gas and aqueous phases were simulated using TD-DFT calculations. In addition, to examine the drug-loading capacity and biocompatibility, up to six 5FU molecules can be attached to Fe 6 @B 40. The solvent effects tend to lower the 5FU adsorption energies to be easily released from nanocages. The greater polarizability and first hyperpolarizability of the 5FU@[Mg@B 40 ], (5FU) 4 @[Fe 4 @B 40 ] and (5FU) 6 @[Fe 6 @B 40 ] systems imply their applications in photonic and extremely effective to improve the NLO performance. These theoretical identifications can provide new insights and guidelines for the future experimental researchers to promote the synthesis and application of metalloborospherenes (Fe 4 @B 40 and Fe 6 @B 40) in drug-loading capacity. [ABSTRACT FROM AUTHOR]

The Excited State Intramolecular Proton transfer in 2E6M occurs in apolar and weekly polar solvents. In strongly polar acetonitrile, the single fluorescence band belongs only to the primarily excited hydrogen bonded (N) form and not to the tautomer (T) after the proton transfer. It is confirmed by TD-DFT calculations, TCSPhC and femtosecond fluorescence up-conversion measurrements. [Display omitted] • DFT and TD DFT calculations reveal the CT nature of both tautomeric forms. • In strongly polar solvents the conditions for ESIPT are unfavorable. • Fluorescence lifetime in D 2 O (100–120 fs) is ∼40 times shorter than in MeOH. • In protic solvents the ESIPT in 2E6M is the solvent assisted proces. In this study we have investigated 2-ethylamino-4-nitro-6-methyl pyridine N-oxide (2E6M) molecule that belongs to important group of Proton Coupled Electron Transfer (PCET) compounds where both the charge transfer (CT) and proton transfer processes in excited states may proceed. In this case, this is possible due to the donors and acceptors of electrons and protons in this system, as well as due to the presence of intramolecular {N-H... O [2,566(3) Å}, hydrogen bond.Using stationary and time-resolved spectroscopy, as well as quantum chemical calculations on the DFT and TD DFT B3LYP/6-31G (d,p) level of theory, a partial CT nature of the S 0 → S 1 transition in both tautomeric forms (N and T) has been revealed. Additionally, the excited state intramolecular proton transfer (ESIPT) process shown to be more favorable in apolar and weakly polar solvents than in strongly polar acetonitrile (E N(S1) > E T(S1). The displacement of charge from the amine group and the ring to the nitro group has been observed on the changing shapes of the HOMO and LUMO orbitals involved in this transition what further quantitatively allowed to realize the increase in the dipole moment of both forms in the electronic excited state. The calculations show that in two solvents with radically different polarity (heptane, acetonitrile), dipole moments of both forms are very similar [in acetonitrile u N (S 1) and u T (S 1) are 11.0 D and 11.5 D, respectively]. Hence, in polar media both forms can be stabilized in a comparable manner. This made it difficult for us to assign a single fluorescent band in acetonitrile to one of the tautomeric forms. However, it seems that due to application of time-resolved spectroscopy, this problem has been clarified. The TCSPC decay curve in acetonitrile with an ultrafast lifetime assigned to the (N) form, along with the femtosecond up-conversion signals that demonstrated only an ultrafast decay without any rise-time of a new excited (T) species, allowed us to conclude that in 2E6M in strongly polar solvent the ESIPT does not occur.The unique fluorescence band origins from the (N) form. In protic solvents, the significant kinetic isotopic effects have provided us with conclusive evidence for the presence of the solvent-assisted ESIPT process. Furthermore, it was noticed that the fluorescence lifetime in D 2 O (100–120 fs) estimated from the up-conversion signals is about 40 times shorter relative to methanol. This may suggest that the sine qua non for the ESIPT process in 2E6M in protic solvents is the formation of a complex with a solvent molecule in the hydrogen bridge between the proton donor and proton acceptor, respectively. [ABSTRACT FROM AUTHOR]

Reaction of the known cycloplatinated (II) complexes [PtAr(C^N)(SMe 2 )], in which Ar= p– MeC 6 H 4 or p– MeOC 6 H 4 and C^N= 2-phenylpyridinate (ppy) or benzo[h]quinolinate (bhq), with 0.5 equivalent of the bidentate phosphine ligand 1,1′–bis(diphenylphosphino)acetylene, dppac, in acetone at room temperature gave the symmetrical binuclear cycloplatinated(II) complexes [Pt 2 Ar 2 (C^N) 2 (μ–dppac)], 1–4 , in which dppac acts as a bridging bidentate ligand. All the complexes were fully characterized using multinuclear ( 1 H, 31 P and 195 Pt) NMR spectroscopy and the complex [Pt 2 ( p– MeC 6 H 4 ) 2 (ppy) 2 (μ–dppac)], 1 , was further identified by single crystal X-ray structure determination. Additional information about the geometries and electronic spectra of these cycloplatinated (II) complexes are discussed. Effects of aryl and C^N ligands on the luminescent properties of the complexes were also investigated that are complying well with the related DFT/TD-DFT calculations. [ABSTRACT FROM AUTHOR]

A novel Schiff base derivative containing 1, 2, 4-triazole nucleus (TMPIMP) was synthesized from 4- [1,2,4] triazol-1-ylmethyl-phenylamine and salicylaldehyde in the presence of glacial acetic acid in an ethanolic medium. The synthesized compound was characterized by 1 H-NMR, IR and UV spectral analysis. The excitation and emission spectra of triazolyl methyl phenyl imino methyl phenol (abbreviated as TMPIMP) were recorded in various solvents to investigate their solvatochromic behaviour. Dipole moments of the two electronic states of TMPIMP were calculated from solvatochromic spectral shifts. These were correlated with refractive index (η) and dielectric constant (ε) of various solvents. Theoretical calculations were performed to estimate the excited state dipole moment on the basis of different solvent correlation methods, like the Bilot–Kawski, Bakhshiev, Lippert–Mataga, Kawski–Chamma-Viallet and Reichardt methods. The dipole moment in the excited state was found to be higher than that in the ground state due to a substantial redistribution of electron densities and charges. Using a multiple regression analysis, the solvent–solute interactions were determined by means of Kamlet Taft parameters (α, β, π*). Computational studies were performed by Gaussian 09 W software using a time-dependent density functional theory (TD-DFT) in order to calculate the atomic charges and frontier molecular orbital energies in the solvent phase. The calculations indicated that the dipole moment of the molecule in an excited state is much higher than that in a ground state. The chemical stability of TMPIMP was determined by means of chemical hardness (η) using HOMO-LUMO energies. The reactive centers in the molecule were also identified by molecular electrostatic potential (MESP) 3D plots as a result of TD-DFT computational analysis. [ABSTRACT FROM AUTHOR]

Efavirenz, commercially known as Sustiva® or Stocrin®, is a first-line antiretroviral treatment for HIV/AIDS. The clinical efficacy of efavirenz is, however, hindered by its solubility. We sought to investigate the solute–solvent effects of efavirenz by means of a combined qualitative study implementing UV–visible spectrophotometry, 1 H NMR spectroscopy and time-dependent density functional theory (TD-DFT) calculations. The UV spectrum displayed two main absorbance maxima, band I and band II at 246–260 and 291–295 nm, respectively. A general bathochromic shift was noticed from the non-polar solvent cyclohexane to the most polar solvent DMSO (≈ 13.69 nm) in band I and a smaller bathochromic (≈ 2.17 nm) and hyperchromic shift was observed in band II. We propose that these observations are due to the role of the amino (NH) and carbonyl (CO) functionalities which induce charge-transfer and intra- and inter-molecular hydrogen bonding. The aromatic and amine protons showed the most deshielded effects in the observed chemical shifts (δ) in the more polar DMSO- d 6 solvent relative to CDCl 3 . The 1 H NMR chemical shifts observed are due to the increased delocalization of the lone pair electrons of the amino nitrogen with increased polarity of the more polar DMSO solvent. The theoretical reproduction of the UV and 1 H NMR spectra by means of TD-DFT is in good agreement with the experimental results. [ABSTRACT FROM AUTHOR]

We report the linear and nonlinear optical properties of the star shaped ferrocenyl substituted thiophene triazines 1 – 4 . The red shift in π→π* absorption and enhancement in molar extinction coefficient (ε) in triazines 1 – 4 were found to be directly proportional to the conjugation length, whereas the HOMO-LUMO gap in triazines 1 – 4 were found to be inversely proportional to the conjugation length. The time dependent density functional theory (TD-DFT) at CAM-B3LYP and B3LYP calculations on triazines 1 – 4 were performed, in which TD-DFT/CAM-B3LYP results show good agreement with the experimental results. The nonlinear optical properties of triazines 1 – 4 were studied under femtosecond laser pulse excitation at 800 nm using the Z-scan technique. Large two-photon absorption coefficient value (1.8 × 10 −13 m/W) was obtained for highly conjugated triazine 4 . These triazines can serve as on optical limiter toward, high intensity short pulses. [ABSTRACT FROM AUTHOR]

Two new copper(II) complexes with polypyridyl ligands, [Cu(phen) 2 (H 2 O)](ClO 4 ) 2 ( 1 ) and [Cu(bipy) 2 (NO 3 )]ClO 4 ( 2 ) (phen = 1,10-phenanthroline and bipy = 2,2′-bipyridyl) have been synthesized and characterized by elemental analysis, FAB (fast atomic bombardment), magnetic measurements, electronic absorption, conductivity measurements, cyclic voltammetry (CV) and electronic paramagnetic resonance (EPR) spectroscopy. The structures of 1 and 2 were determined by single crystal X-ray crystallography. Both complexes 1 and 2 show a distorted trigonal bipyramidal (DTBP) geometry around the copper(II) metal center. The 3-D supramolecular structures of the complexes are totally guided by H-bonding. The geometries of both complexes were optimized in the singlet ground state by DFT calculations. Electronic spectra of the complexes are explained using TD-DFT calculations. The results from density functional studies have been compared with the X-ray data. Biological activities, in terms of the superoxide dismutase (SOD) copper(II) complex, have also been measured. The superoxide dismutase activity reveals that the complexes catalyze the fast disproportionation of superoxide in DMSO solution. [ABSTRACT FROM AUTHOR]

[Display omitted] • PAOP with AIE-active feature and monomer emission in diluted solvent is successfully synthesized. • In situ group replacement method is developed to transform ACQ-active materials to AIE molecule. • A new silsesquioxane-based fluorescent material of PAOP is constructed from phthalic anhydride and octaaminopropylsilsesquioxane. • PAOP could realize dual-channel selective detection of F-. • DFT and TD-DFT calculations were used to investigate structures and electronic properties of the formed complex. Fluoride plays an indispensable role in physiological process, it is widely used in the fields of toothpaste and medicine, etc. However, excess fluoride ions can cause acute gastritis, malignant skeletal fluorosis and kidney problems. Consequently, the accurate identification of fluoride is of great importance. Therefore, we functionalized octa (aminopropyl) polyhedral oligomeric silsesquioxane (OAP-POSS) (T 8) with traditional aggregation caused quenching (ACQ) aromatic luminogens to obtain phthalic-anhydride-OAP-POSS (PAOP), which not only solves the problem of ACQ, but also can be used to identify fluorine ions. The identification limit was 1.27 × 10-5 mol/L in THF(tetrahydrofuran) and 5.86 × 10-4 mol/L in DMSO (dimethyl sulfoxide). Moreover, through theoretical calculation (DFT and TD-DFT) and experiment, we further studied the action mechanism of fluorine on silicon and explored the possibility of F- encapsulated in POSS cage. [ABSTRACT FROM AUTHOR]

[Display omitted] • Quinoxalinone-based chromophores with aniline/heteroaryl donors have been synthesized. • Experimental and theoretical absorption spectra of chromophores were compared. • First hyperpolarizability of chromophores was calculated at DFT level. • NLO coefficients of PMMA doped with the chromophores were measured by SHG techique. Four novel push-pull tricyanofuran-based chromophores with vinylene-quinoxalinone-vinylene π-conjugated bridge and aniline type donor with phenyl moiety either introduced into the donor/acceptor as substituent or fused with aniline in carbazole and phenothiazine structures have been synthesized and their linear and nonlinear optical properties were systematically investigated by UV–Vis spectroscopy and DFT calculations. Addition of benzene ring as substituent to the chromophore leads to moderate (22–36 pm/V) macroscopic NLO activity of composite chromophore/PMMA materials, while guest-host polymers doped with chromophores with fused heterocyclic donor moiety demonstrate higher d 33 values up to 47 pm/V. Chromophore-containing polymer films preserve more than 90% of d 33 after 1000 h at ambient temperature. [ABSTRACT FROM AUTHOR]

A fluorescent chemosensor based on dimethylaminocinnamaldehyde-aminothiourea (DA) has been designed, synthesized, and applied with a combined theoretical and experimental study. The synthetic path, optimized molecular structure and characteristics of DA were carried out using the calculations at the B3LYP/LanL2DZ level of theory. The experimental investigations have a good agreement with the theoretical results. DA can be used as a chemosensor for simultaneous quantification of silver, copper, and mercury ions in aqueous solution at the ppb level. The stable geometric structures of the complexes between DA and Ag + , Hg 2+ , Cu 2+ with stoichiometry of 1:1, 2:1, and 2:1, have been found and investigated for electronic properties and fluorescence quenching phenomena by using Atoms in Molecules (AIM) and Natural Bond Orbitals (NBO) analyses. [ABSTRACT FROM AUTHOR]

Berberine ( Bn ), an important traditional medicinal herb with anticancer, antitumour and antidiabetic activities, is effectively utilized as a sensing probe for silver ion with good sensitivity and selectivity, using absorbance and fluorescence studies. The effect of presence of other metal ions with Bn is also investigated and Bn is found to be selective towards Ag + ion over other metal ions such as Cu 2+ , Zn 2+ , Sn 2+ , Ni 2+ , Ba 2+ , Bi 2+ , Pb 2+ , Co 3+ , In 3+ , Mn 2+ , Fe 2+ , Fe 3+ , Li + , Hg 2+ and Ca 2+ with a detection limit of 0.1 × 10 −4 mol L −1 . The colour changes from yellow to orange when Ag + ion is added and other metal ions failed to show any visible colour change. The effective quenching of Bn upon binding with Ag + ion is attributed to suppression of intramolecular charge transfer (ICT). [ABSTRACT FROM AUTHOR]

[Display omitted] • Spectroscopic investigations of both ground and excited states of the dyes under the study. • Photophysical interactions between DOLDs and TPPS. • TD-DFT/DFT theoretical calculations and their matching with the measured spectra and proofing the partial positive charge on DOLDs. • Effect of negatively charged AgNPs on FRET from DOLDs to TPPS. The proposed enhancement mechanism is a kind of nano-immobilization. • Theoretical and experimental results are matched. Porphyrin derivatives are known singlet oxygen sensitizers in photodynamic therapy (PDT). Energy transfer from a class of diolefinic laser dyes (DOLDs) as energy donors to the sodium salt of meso-tetrakis (4-sulfonatophenyl) porphyrin (TPPS) as the accepter of energy would extend the range of photon harvesting down to the UV-region. Energy transfer was substantially enhanced in the presence of metallic silver nanoparticles (AgNPs), as revealed by steady-state emission spectroscopy, lifetimes, and quantum mechanics. DOLDs under investigation are 2,5-distyrylpyrazine (DSP), 1,4-bis (β-pyridyl-2 vinyl) benzene (P2VB), and 1,4 bis (2-methylstyryl) benzene (MSB) as efficient donors of intense absorption in the UV-region. AgNPs enhance the rate of energy transfer from DOLDs to TPPS via bringing donor and acceptor into close- proximity with a concomitant increase in dipole–dipole interaction between excited state donor and ground-state acceptor. The DOLDs molecular structures were optimized using the DFT/CAM-B3LYP/6-311G++ (d, p) level of theory. The calculated electronic absorption spectra for the studied DOLDs in the gaseous phase and methanol solvent were studied using the time-dependent density functional theory (TD-DFT) at M06-2X/6-311G++ (2d,2p) level. The calculated absorption/emission spectra for DSP laser dye in methanol are obtained at the TD/ M06-2X/6-311G++(2d, 2p) method. Notably, all theoretical results of the molecular structures under study highly agreed with the practical optical results. Energy transfer rate constants (k ET) amid energy donor/acceptor pairs were determined by Stern-Volmer constants (KSV) and donors' lifetime measurements. The KSV values indicate an enhanced Fluorescence Resonance Energy Transfer (FRET) efficiencies in the presence of negatively charged AgNPs. The critical transfer distances R o were determined from the spectral overlap between the emission spectrum of donor and absorption spectrum of TTPS. These outcomes propose the application of designed metal-enhanced FRET for energy-transfer-based assays and photodynamic therapy (PDT) applications. [ABSTRACT FROM AUTHOR]

Abstract: Spectral-luminescence properties of several dimethylaminostyryl-β-diketonates of boron difluoride with different α-substituents have been investigated through stationary and time-resolved spectroscopy. Quantum chemistry studies of the structure of excited states of 2,2-difluoro-4-(4′-dimethylaminostyryl)-6-phenyl-1,3,2-dioxaborine have been performed. Two luminescence centers have been revealed for the compound under study: an intensive band in the red–orange region of the spectrum caused by an S1–S0 transition and a short-wave luminescence in the blue region of the spectrum caused by an S2–S0 transition. [Copyright &y& Elsevier]

The multi-step synthesis, structural and optical properties of original luminescent borate complexes derived from 2-(2'-hydroxybenzofuran)benzoxazole (HBBO) are reported. Functionalization at position 3 of the benzofuran ring was readily achieved through an electrophilic cyclization key step followed by a Sonogashira cross-coupling reaction. The optical properties of the resulting boron difluoride dyes highlight different photophysical behaviors depending on the nature of the substitution at position 3 of the benzofuran core (tBu-phenylacetylene or NnBu2-phenylacetylene). The NnBu2-phenylacetylene moiety favors a sizeable intramolecular charge transfer as evidenced by a strong solvatochromism; a feature further confirmed by ab initio calculations. [ABSTRACT FROM AUTHOR]

Abstract: Magnetic circular dichroism (MCD) spectroscopy and time-dependent density functional theory (TD-DFT) calculations are used to analyze the electronic structure and optical properties of low-symmetry subnaphthalocyanine analogs with AAB and ABB structures formed during mixed condensations of tetrafluorophthalonitrile and 2,3-naphthalenedicarbonitrile. The results demonstrate that trends observed in the properties of phthalocyanine analogs can be used to fine tune the optical properties so that the Q(0,0) bands lie in the red region, in a manner that does not significantly destabilize the highest occupied molecular orbital (HOMO) energy relative to that of the parent subphthalocyanine ligand. Attempts to study the spectroscopy of anion radical species proved unsuccessful, since they proved to be unstable. [Copyright &y& Elsevier]

Highlights: [•] Fenoterol derivatives display stereoselective activity as β2-AR agonists. [•] A full stereochemical characterization of fenoterol derivatives is crucial. [•] A combined ECD and TD-DFT analysis was performed on fenoterol stereoisomers. [•] TD-DFT calculations confirm the stereochemistry of fenoterol stereoisomers. [•] DFT geometries reveal different conformational patterns among diastereomers. [Copyright &y& Elsevier]

Highlights: [•] Synthesis of novel dimethyl 2-(3-methylbut-2-enyl)malonate substituted zinc and platinum phthalocyanines by green chemistry is reported. [•] The bulky ester substituents enhance the solubility of the Pt(II)Pc complexes and minimize the extent of aggregation. [•] The Pt(II) has a higher singlet oxygen quantum yield due to the heavy atom effect. [•] TD-DFT calculations were carried out to compare the electronic structures of the Pt(II) and Zn(II) complexes. [ABSTRACT FROM AUTHOR]

Abstract: In this study, we demonstrate a successful synergy between theory and experiment and report on the photophysical properties of a recently synthesized series of substituted 2-benzoylmethylenequinoline difluoroboranes with a view towards the effect of substitution on their properties. In general difluoroboranes are known to have a bright fluorescence but for some analogs the properties are not fully understood. Quantum chemistry methods have been applied in order to explain a complex structure of the absorption and emission spectra and to gain an insight into the charge redistribution upon the excitation of the investigated molecules. We demonstrate that the spectra of this important class of compounds can be satisfactorily simulated using quantum chemistry methods. In particular, the absorption and emission band structure was resolved and the spectral features were assigned to C–H wagging and skeletal vibrations of the polycyclic core. [Copyright &y& Elsevier]