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Piperazine appended naphthalimide-BODIPYs (NPB1–NPB4) exhibiting solvatochromism and aggregation-induced emission with a large Stokes shift (up to 146 nm) have been described. Separation of naphthalimide and BODIPY fluorophores by piperazine in these conjugates creates a donor–acceptor system and induces twisted intramolecular charge transfer, in addition to photoinduced electron transfer. The crucial role of naphthalimide, the alkyl chain length, the piperazine ring, and the solid-state packing on AIE has been extensively investigated by various studies. Superior cell permeability coupled with bio-compatibility of these conjugates offers a unique opportunity for their potential applications in live cell lysosomal tracking. [ABSTRACT FROM AUTHOR]

Abstract: Epitope imprinting is a promising technique for fabrication of novel diagnostic tools. In this study, an epitope imprinted methodology for recognition of target epitope sequence as well as targeted protein infused by bacterial infection in blood samples of patients suffering from brain fever is developed. Template sequence chosen is a ferric iron binding fbp A protein present in Neisseria meningitidis bacteria. To orient the imprinting template peptide sequence on gold surface of electrochemical quartz crystal microbalance (EQCM), thiol chemistry was utilized to form the self‐assembled monolayer on EQCM electrode. Here, synergistic effects induced by various noncovalent interactions extended by multiple monomers (3‐sulfopropyl methacrylate potassium‐salt and benzyl methacrylate) were used in fabricating the imprinting polymeric matrix with additional firmness provided by N,N‐methylene‐bis‐acrylamide as cross‐linker and azo‐isobutyronitrile as initiator. Extraction of template molecule was carried out with phosphate buffer solution. After extraction of epitope molecules from the polymeric film, epitope molecularly imprinted polymeric films were fabricated on EQCM electrode surface. Nonimprinted polymers were also synthesized in the similar manner without epitope molecule. Detection limit of epitope molecularly imprinted polymers and imprinting factor (epitope molecularly imprinted polymers/nonimprinted polymers) was calculated 1.39 ng mL−1 and 12.27 respectively showing high binding capacity and specific recognition behavior toward template molecule. Simplicity of present method would put forward a fast, facile, cost‐effective diagnostic tool for mass health care. [ABSTRACT FROM AUTHOR]

Fluorescent azo-phenol BODIPYs (1–3) have been obtained by the substituent (–OCH3/–CH3) directed synthesis of ortho (L1) and para (L2–L3) azo-phenol aldehydes. These display aggregation caused quenching (ACQ, 1) and aggregation induced emission enhancement (AIEE, 2 and 3) depending on the position of azo relative to the phenolic hydroxyl group. An intriguing time dependent morphological transition from nanospheres to ordered nanorods and subsequent emission changes in AIEE active azo-phenol BODIPYs have been successfully realized by time dependent fluorescence, scanning electron (SEM), transmission electron (TEM) and fluorescence optical microscopy (FOM) studies. The existence of one-dimensional (1D) nanorods as ultimate species in these compounds (2–3) has been supported by crystal packing patterns. Diverse aggregated forms and hierarchical nanostructures have been related to variable extents of fluorescence enhancement. The plausible charge transfer process and its role in AIEE have been supported by DFT studies. [ABSTRACT FROM AUTHOR]

Synthesis of terpyridyl based ligands 3-([2,2′:6′,2′′-terpyridin]-4′-yl)-7-methoxy-2-(methylthio)-quinolone, (L1); 3-([2,2′:6′,2′′-terpyridin]-4′-yl)-6-methoxyquinolin-2(1H)-one, (L2); 3-([2,2′-:6′,2′′-terpyridin]-4′-yl)-6-methylquinolin-2(1H)-one (L3) and cyclometalated iridium(iii) complexes [[Ir(ppy)2L1]+PF6− (1), [Ir(ppy)2L2]+PF6− (2), [Ir(ppy)2L3]+PF6− (3) (2-phenylpyridine = Hppy)] involving these ligands has been described. The ligands L1–L3 and complexes 1–3 have been thoroughly characterized by elemental analyses, spectral studies (IR, 1H, 13C NMR, UV/vis and fluorescence) ESI-MS, and the structure of 3 has been unambiguously authenticated by single crystal X-ray analyses. UV/vis, fluorescence and circular dichroism spectroscopic studies showed rather efficient binding of 1 with CT-DNA (calf thymus DNA) and BSA (bovine serum albumin) relative to 2 and 3. Molecular docking studies unveiled binding of 1–3 with minor groove of CT-DNA via van der Waal's forces and electrostatically with the hydrophobic moiety of HSA (human serum albumin). The ligands and complexes exhibited moderate cytotoxicity towards MDA-MB-231 (breast cancer cell line) and significant influence on HeLa (cervical cancer cell line) cells. Cytotoxicity, morphological changes, and apoptosis have been followed by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazoliumbromide) assay, Hoechst 33342/PI (PI = propidium iodide) staining, cell cycle analysis by FACS (fluorescence activated cell sorting), and ROS (reactive oxygen species) generation by DCFH-DA (dichlorodihydrofluorescein diacetate) dye. Confocal microscopy images revealed that the drug efficiently initiates apoptosis in the cell cytosol. The IC50 values showed superior cytotoxicity of 1–3 against the HeLa cell line relative to cisplatin, and their ability to induce apoptosis is in the order 1 ＞ 2 ＞ 3. [ABSTRACT FROM AUTHOR]

A series of copper(ii) complexes (1–9 and 3′) derived from bis-dipyrrin ligands (L1–L9 and L3′) with diverse spacer lengths [–(CH2)n–] have been described. Structural diversities in these complexes have been explicitly established by spectral and structural studies on these and a closely related nickel(ii) complex (3′′). All the ligands and complexes have been thoroughly characterized by spectroscopic studies (ESI-MS, IR, 1H, 13C NMR, UV/vis) and structures of 2, 3′, 3′′, 6, 8 and 9 were determined by X-ray single crystal analyses. It has been unambiguously established that ligands with n≤ 6 gave heteroleptic binuclear (1–5), while those with n≥ 7 yielded homoleptic mononuclear (6–9) bis-dipyrrinato complexes. Spectral and structural studies revealed distorted square planar (1–5) and distorted tetrahedral geometries (6–9) about the copper(ii) centre in these complexes which has further been evidenced by EPR and electrochemical studies. Structural differences based on the odd and even number of methylene spacers in these complexes have been supported by DFT studies. A line between the syn- and anti-conformations of the complexes has been drawn on the basis of a limiting spacer length. [ABSTRACT FROM AUTHOR]

Synthesis of four new arene ruthenium(II) complexes [(η 6 -C 10 H 14 )RuCl(MFPdpm)] ( 1 ); [(η 6 -C 12 H 18 )Ru-Cl(MFPdpm)] ( 2 ); [(η 6 -C 10 H 14 )RuCl(PFPdpm)] ( 3 ) and [(η 6 -C 12 H 18 )RuCl(PFPdpm)] ( 4 ) containing dipyrrin ligands 5-(4-fluoro)phenyldipyrromethene (MFPdpm) and 5-(penta-fluoro)phenyldipyrromethene (PFPdpm) have been described. The ligands and complexes have been thoroughly characterized by elemental analyses, spectroscopic studies (ESI-MS, IR, 1 H, 13 C NMR, UV–Vis) and structure of the representative complex 4 determined by X-ray single crystal analyses. DNA binding activities of 1 – 4 have been investigated by UV–Vis and fluorescence spectroscopy and their binding through the minor groove of DNA has been established by molecular docking studies. The complexes 1 – 4 exhibit significant cytotoxicity toward human lung cancer cell line (A549). Cytotoxicity, morphological changes, and apoptosis studies have been evaluated through MTT assay, Hoechst 33342/PI staining, and cell cycle analysis by fluorescence activated cell sorting (FACS). In vitro antitumor activity and cytotoxicity of the complexes lie in the order 4 > 3 > 2 > 1 . [ABSTRACT FROM AUTHOR]

A pioneering approach towards controlling the efficiency of saponification assisted gelation in ethyl ester based ZnII-complexes have been described. Using four new ester containing bis-salen ZnII complexes (C1-C4) involving different para-azo phenyl substituted ligands it has been clearly shown that gelation efficiency is greatly influenced by the electronic effects of the substituents (-H (C1), -CH3 (C2), -NO2 (C3), and -OCH3 (C4)). Morphological, photophysical, and rheological investigations corroborated the experimental observations well and established that gelation efficiency was enhanced with electron-withdrawing characteristics of substituents (C4

New terpyridyl ligands TP1, TP2 and cyclometalated iridium(III) complexes 1 and 2 based on these ligands have been synthesized. The ligands and complexes have been characterized by elemental analysis and spectroscopic studies (ESI-MS, 1H and 13C NMR, UV/Vis, fluorescence). The molecular structure of 1 has been verified by X-ray single-crystal analysis. It has been unambiguously established that variation of the substituents on 1 and 2 leads to molecular aggregation in 1, while 2 remains nonaggregated. Furthermore, complexes 1 and 2 have been successfully utilized as capping agents for the stabilization of gold nanoparticles (AuNPs). It is of note that 1 forms discretely, while 2 aggregates AuNPs through the assemblage of ultrasmall nanoparticles. It has been affirmed by 1H NMR titration studies that - NH groups from 1 and 2 are involved in the capping of AuNPs. The role of simple structural variations in directing molecular and nanoaggregation has been clearly established for the first time by spectroscopic (UV/Vis, fluorescence, 1H NMR titration) and morphological studies [SEM, TEM, EDX (energy-dispersive X-ray), DLS (dynamic light scattering)]. [ABSTRACT FROM AUTHOR]

The proficiency of the cyclometalated iridium complexes [(η5-C5Me5)IrCl(L1)] (1), [(η5-C5Me5)IrCl(L2)] (2) and [(η5-C5Me5)IrCl(L3)] (3) has been examined towards photochemical water oxidation. The involvement of Ir(iv/v) in the catalytic process has been explored via CV, UV/vis, XPS spectroscopic studies and appreciable TON relative to the theoretical value of 1 from GC. [ABSTRACT FROM AUTHOR]

One-dimensional nanostructures with aggregation-induced emission (AIE) properties have been fabricated to keep the pace with growing demand from optoelectronics applications. The compounds 2-[4-(4-methylpiperazin-1-yl)benzylidene]malononitrile ( PM1), 2-{4-[4-(pyridin-2-yl)piperazin-1-yl]-benzylidene}malononitrile ( PM2), and 2-{4-[4-(pyrimidin-2-yl)piperazin-1-yl]benzylidene}malononitrile ( PM3) have been designed and synthesized by melding piperazine and dicyanovinylene to investigate AIE in an asymmetric donor-acceptor (D-A) construct of A′-D-π-A- topology. The synthetic route has been simplified by using phenylpiperazine as a weak donor (D), dicyanovinylene as an acceptor (A), and pyridyl/pyrimidyl groups ( PM2/PM3) as auxiliary acceptors (A′). It has been established that A′ plays a vital role in triggering AIE in these compounds because the same D-A construct led to aggregation-caused quenching upon replacing A′ with an electron-donating ethyl group ( PM1). Moreover, the effect of restricted intramolecular rotation and twisted intramolecular charge transfer on the mechanism of AIE has also been investigated. Furthermore, it has been clearly shown that the optical disparities of these A′-D-π-A architectures are a direct consequence of comparative A′ strength. Single-crystal X-ray analyses provided justification for role of intermolecular interactions in aggregate morphology. Electrochemical and theoretical studies affirmed the effect of the A′ strength on the overall properties of the A′-D-π-A system. [ABSTRACT FROM AUTHOR]

With intent to fine tune the morphological and photophysical properties, three novel AIE luminogens (BQ1–BQ3) based on quinoline–BODIPY have been synthesized. A judicious choice of substituents (–H, –CH3, –OCH3) in these systems led to nanoballs in BQ1 and BQ2, while in BQ3 it led to reticulated nanofibers with diverse photophysical behaviours. [ABSTRACT FROM AUTHOR]

An expeditious synthesis of new click reaction-based BODIPY–piperazine conjugates separated by alkyl spacers (4–7) has been described. The compounds under investigation have been thoroughly characterized by various physicochemical techniques viz., elemental analyses, IR, HRMS, NMR (1H, 13C, 11B and 19F), electronic absorption, emission and theoretical studies. The comparative sensing abilities of 4–7 toward a range of metal ions have been investigated by various methods. Among these compounds, only 7 exhibited appreciable selectivity towards Hg2+, while the others remained inactive in the presence of various metal ions. Binding constant and Job's plot analysis indicated 1 : 1 stoichiometry between 7 and Hg2+. HRMS data and theoretical studies undoubtedly indicated the formation of a 7·Hg2+ complex and interaction of Hg2+ with the probe via nitrogen atoms in the piperazine and triazole units. [ABSTRACT FROM AUTHOR]

Carbohydrate based fluorescent sensors S1 and S2 have been developed by fluorogenic dual click chemistry and are characterized by various spectroscopic techniques. Both the fluorescent probes displayed highly selective detection of Cu2+ ions by means of fluorescence quenching. The job plot experiment suggested 1:1 complexation of probes S1 and S2 with Cu2+ ions having detection limit of 6.99 μM and 7.30 μM, respectively. The binding constants for S1-Cu2+ and S2-Cu2+ complexation were evaluated to be 3.34 x 10³ M-1 and 5.93 x 10³ M-1, respectively. [ABSTRACT FROM AUTHOR]

The prevalence of the D–A strategy in achieving red-shifted emission has been established through designing D–A molecules of D–A–D and A–D–A constructs. Architectural control over such D–A systems integrates solid state NIR emission with lysosome tracking and sets a multifarious goal of photophysical modulation in a comprehensive way. In particular, two compounds, CPM–1 (D–A–D) and CPM–2 (A–D–A), have been synthesized by introducing carbazole-based donors and difluoroboron acceptors. Lysosome targeting and imaging have been achieved through incorporation of a morpholine unit, which ultimately imparts viscosity sensitivity to the construct. The fluorophores exhibited significant emission in solution along with distinctive solvatochromism, viscochromism and TICT. A comparative account of these competitive photophysical properties revealed the superior charge transfer properties of the A–D–A construct (CPM–2), while the D–A–D molecule (CPM–1) was found to be a better molecular rotor with marked viscochromism. The solid state NIR emission has been found to be much more intense in CPM–1 relative to CPM–2, which further highlights the influence of structural aspects on photophysical behvaiour. Theoretical studies further established the distinctive characteristics of ground and excited states in these compounds. Owing to its excellent viscochromic behvaiour, CPM–1 has been successfully utilized in lysosome targeting in wild-type Drosophila fly gut tissues through co-localization studies. [ABSTRACT FROM AUTHOR]

• Promising G-quadruplex binders: chroman derivatives ligands & their BF2-complexes. • These compounds stabilize parallel and mixed hybrid G-quadruplex structures. • In vitro and cellular studies: biophysical analyses demonstrate binding affinity in both contexts. • Molecular docking: computational study supports binding of chroman complexes to G-quadruplex. • Potential fluorescent ligands: these compounds offer new options for G-quadruplex targeting ligands. Currently, G-quadruplex structure targeting strategies are considered as a promising anticancer approach. The purpose of this research is to expand the options for G-quadruplex targeting ligands, particularly emphasizing fluorescent ligands. Our study contributes to the field by providing additional choices for G-quadruplex binders with a notable focus on selectivity towards G-quadruplex topology over duplex DNA. In the search of selective and potent G-quadruplex binders, here we discuss an analysis of a few chroman derivatives ligands named A and C and their respective borondifluoride complexes B and D as a quadruplex targeting compounds which found to stabilize G-quadruplex structure. To investigate the binding characteristics of these molecules with G-quadruplex vs. duplex selectivity, In vitro biophysical studies were performed by steady-state fluorescence, UV–visible titration, fluorescent TO displacement assay, CD thermal melting, circular dichroism spectroscopy, and cellular imaging by employing both telomeric and PRCC G-quadruplex forming sequences. Our investigation shows that these chromam ligands and their complexes are able to selectively bind and stabilize parallel and mixed hybrid topology of G-quadruplex both In vitro and in cellular conditions. A molecular docking and MD simulation study also suggests the binding of these compounds with G-quadruplex conformation. Collectively our study suggests these chroman complexes for the first time as a potentially useful fluorescent chemical product for G-quadruplex specific ligands and expands an option for G-quadruplex targeting ligands. [Display omitted] [ABSTRACT FROM AUTHOR]

Efficacy of the ferrocene appended piano-stool dipyrrinato complexes [(η6-C6H6)RuCl(fcdpm)] (1), [(η6-C10H14)RuCl(fcdpm)] (2), [(η6-C12H18)RuCl(fcdpm)] (3) [(η5-C5Me5)RhCl(fcdpm)] (4) and [(η5-C5Me5)IrCl(fcdpm)] (5) [fcdpm = 5-ferrocenyldipyrromethene] toward anticancer activity have been described. Binding of the complexes with calf thymus DNA (CT-DNA) and BSA (bovine serum albumin) have been thoroughly investigated by UV-Vis and fluorescence spectroscopy. Binding constants for 1-5 (range, 104-105 M-1) validated their efficient binding with CT-DNA. Molecular docking studies revealed interaction through minor groove of the DNA, on the other hand these also interact through hydrophobic residues of the protein, particularly cavity in the subdomain IIA. In vitro anticancer activity have been scrutinized by MTT assay, acridine orange/ethidium bromide (AO/EtBr) fluorescence staining, and DNA ladder (fragmentation) assay against Dalton's Lymphoma (DL) cells. Present study revealed that rhodium complex (4) is more effective relative to ruthenium (1-3) and iridium (5) complexes. [ABSTRACT FROM AUTHOR]

Three novel chalcone based asymmetrical D–A–D′–A'chromophores (C1 – C3) have been designed and synthesized with intent to achieve dual state emission. It has been contemplated that introducing both flexible and rigid moieties to the D–A core will suffice for the emission in solution as well as solid state. In this regard flexible piperazine unit has been introduced along with rigid polyaromatic hydrocarbons anthracene, C1 ; pyrene, C2 and phenothiazine, C3 to afford an asymmetric D–A construct. The compounds have been thoroughly characterized by spectroscopic studies (1H, 13C, ESI–MS, UV/Vis and fluorescence). The compounds C1–C3 display varying degree of dual state emission as envisaged by photo-physical investigation in solution, aggregated and solid state along with quantum yield assessment. Notably the aggregation has been instigated in these compounds by taking advantage of relative hydrophilicity/hydrophobicity of different solvent systems. The revered intramolecular charge transfer (ICT) imparts substantial solvatochromism to these D−A constructs. The prudence of incorporation of heteroatomic phenothiazine unit to the designed chromophores is reflected in superior dual state emission and solvatochromism of C3. In addition, these compounds revealed remarkable acid–induced fluorescence quenching effect in solution and solid state as the emission of C1–C3 could be quenched by trifluoroacetic acid (TFA) significantly. Image 1 [ABSTRACT FROM AUTHOR]

Design and synthesis of novel mono- and dimeric quinazoline derivatives (+)-6-methyl-6-pyridin-2-yl-5,6-dihydrobenzo[4,5]imidazo[1,2- c ]quinazoline ( 1 ) and (+)-6-[(6-methyl-5,6-dihydrobenzo-[4,5]imidazo[1,2-c]quinazolin-6-yl)-pyridin-2-yl]-6-methyl-5,6-dihydro-benzo-[4,5]imidazo-[1,2- c ]quinazoline ( 2 ) have been described. Both 1 and 2 have been characterized by elemental analyses, FT-IR, 1 H and 13 C NMR, HRMS spectroscopic studies and their structures authenticated by X-ray single crystal analyses. Photophysical properties of these compounds have been studied by UV/VIS absorption and fluorescence spectroscopy and transient photoluminescence analysis in solution, powder, and non-doped (neat) and doped vacuum-deposited films. A broad emission spectrum spanning most of the visible range and good thermal stability indicated promising application of 1 and 2 as OLED emitters. Unfortunately, under current flow we observed rapid device degradation, presumably to be related to free –N H moiety in these compounds. [ABSTRACT FROM AUTHOR]

Meticulous attention to details of intramolecular charge transfer (ICT) has proved to be an effective strategy to design donor-acceptor fluorophores equipped with multichromic behaviour. Herein, we report three asymmetric donor-acceptor fluorophores bearing A′−D−A−D−A′ and D′−D−A−D−D′ scaffolds. The D−A−D core has been modified by appending pyridine/pyrimidine as additional acceptor and phenyl as additional donor and piperazine as flexible spacers. The asymmetric scaffold has equipped them with naked-eye solvatochromism even under daylight which further authenticated the effective charge separation in ground as well as excited state. The comparative account of photophysical behaviour displays the varying extent of twisted intramolecular charge transfer (TICT) owing to asymmetry. The interplay of restricted intramolecular rotation (RIR) and TICT leads to AIE induced H+ sensing and reversible acidochromism in PC1 which can be visualized by a comparatively uncommon acid induced emission enhancement. The activation of vibrational bands at higher temperature leads to a rare temperature induced emission enhancement in PC1−PC3. PC1 has been developed as the very first 'turn-on' thermochromic sensor based on β-diketone-boron difluoride (BF 2 bdk) complexes. [Display omitted] • The present work describes the synthesis of β-diketone-boron difluoride (BF 2 bdk) based asymmetric donor-acceptor complexes. • These asymmetric D-A molecules show competitive charge transfer pathways depending upon the type of modification. • The most significant outcome can be visualized in form of visible solvatochromism. • These further display AIE induced H+ sensing and reversible acidochromism. • The activation of vibrational bands at higher temperature leads a rare temperature induced emission enhancement. [ABSTRACT FROM AUTHOR]

Four organometallic complexes [(η6-C6H6)RuCl(pmpzdpm)], 1; [(η6-C6H6)RuCl(pypzdpm)], 2; [(η6-C10H14)RuCl(pmpzdpm)], 3 and [(η6-C10H14)RuCl(pypzdpm)], 4 containing 5-(2-pyrimidyl-piperazine)phenyldipyrromethene (pmpzdpm) and 5-(2-pyridylpiperazine)phenyldipyrromethene (pypzdpm) have been designed and synthesized. The complexes 1–4 have been fully characterized by elemental analyses and spectroscopic studies (ESI-MS, IR, 1H, 13C NMR, UV–vis). Their electrostatic/intercalative interaction with CT DNA has been investigated by UV–vis and competitive ethidium bromide displacement studies while their protein binding affinity toward bovine serum albumin (BSA) was realized by UV–vis, fluorescence, synchronous and three dimensional (3D) fluorescence studies. The interaction with DNA and protein has further been validated by in silico studies. Cellular uptake, in vitro cytotoxicity and flow cytometric analyses have been performed to determine the mode of cell death against the kidney cancer cell line ACHN. Cell cycle analysis suggested that the complexes cause cell cycle arrest in the subG1 phase and overall results indicated that the in vitro antitumor activity of 1–4 lies in the order of 3 ＞ 4 ＞ 1 ＞ 2 (IC50, 7.0 1; 8.0 2; 2.0 3; 4.0 μM, 4). [ABSTRACT FROM AUTHOR]