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We synthesized an efficient dual-directional multivalent pyrene-bearing azaphthalocyanine conjugate (AzaPc–pyrene) and alkyne-terminated azaphthalocyanine (AzaPc1). The ultrafast nonlinear optical ...

The development of new non-aggregated phthalocyanines bearing multivalent saccharide moieties on their macrocyclic rims is of great interest. Many characteristics, including water-solubility, non-toxicity and others, can be feasibly obtained by these amphiphiles which can be considered as a key solution for demonstrating highly efficient photoactive materials in water. Herein, a family of five newly prepared dually directional Zn(ii) containing phthalocyanines (PcG1-4) and azaphthalocyanine (AzaPcG1) glycoconjugates is described. The unique spatial arrangement of the glucoside units based on peripherally hexadeca-(PcG1) and nonperipherally octa-(PcG4) macrocycles provides a fully monomeric behaviour along with a high fluorescence (ΦF∼ 0.21) in aqueous solution. These amphiphiles were characterized by low toxicity, and an extremely low cellular uptake was obtained due to the highly polar nature of the glucoside substituents. Accordingly, their potential as suitable photoactive chromophores for red-emitting extracellular fluorescent probes has been confirmed upon the evaluation of paracellular transport using a layer of MDCKII cells with the permeability coefficient fully comparable with an established evaluator of the integrity of the monolayer.

Asymmetrically substituted zinc phthalocyanine (Pc) derivatives bearing quaternized triazolyl moieties for water solubility and iodine as a heavy metal atom have been investigated as singlet oxygen generators in aqueous media. In addition to the heavy atom effect exerted by iodine covalently bonded to the Pc molecule, a second dimensional effect induced by aggregation which brings the iodine anions of triazolyl units into closer proximity to the Pc core leading to the highest reported singlet oxygen generation for a Pc derivative in water ( Φ Δ = 0.87).

Based on the concept of dual-directionality, the synthesis of two novel zinc(II)-containing phthalocyanine (Pc-ene1) and azaphthalocyanine (AzaPc-ene1) macrocycles bearing dual directional (up/down) allyl moieties on their rims is reported. Their structural identification, that is, NMR, FT-IR, UV-vis, MALDI-TOF spectral data, single crystal X-ray diffraction, and CHN elemental analyses, along with their nonaggregating behaviors in solvated media and crystalline forms has been confirmed.

Derivatized phthalocyanines (Pcs) and their heteroatom analogues, azaphthalocyanines (AzaPcs), bearing a variety of highly active ligands, have many advantageous properties that make them suitable as novel macrocyclic platforms. Many peripherally/non-peripherally functionalized macrocycles have been successfully employed as molecular platforms; however, due to the lack of directional control of the outward-facing reactive species, retaining their planarity while avoiding aggregation was quite challenging. The present work demonstrates the role of dual directionality using multivalent, orthogonal propargyl moieties based on two novel Zn(II)phthalocyanine (Pc1) and azaphthalocyanine (AzaPc1) complexes. These groups prevent the macrocyclic planar cores from self-associating in solution or in the solid state, as confirmed by 1H NMR, UV-Vis and single-crystal X-ray diffraction analyses. Such activated systems are thus highly applicable as key intermediates in the development of “molecular platforms” to generate endless, applicable, non-aggregated macrocyclic materials via a variety of organic transformations, specifically, the powerful click reaction, Cu(I)-catalysed azide–alkyne cycloaddition (CuAAC). In addition to their utility as efficient building blocks suitable for further modification, the photophysical/photochemical properties of these compounds were also investigated to determine their photocatalytic activities for valuable applications, such as in photodynamic therapy (PDT).

Targeting biotin receptors in cancer cells can improve specifying of photosensitizers (PSs) for cancer treatment by photodynamic therapy (PDT) applications. Consequently, there has been extensive research focusing mainly on the design of PSs with optimized pharmaceutical properties and better targeting toward cancer cells. Herein a tailored mono-biotinylated zinc(II) phthalocyanine (Pc-1) substituted with six phenoxy-bis(triazolyl) substituents has been synthesized. This Pc-1 has been further modified to its cationic version (Pc-2) through quaternizing of the triazole moiety to gain water solubility. Both non-ionic zinc(II) phthalocyanine (Pc-1) and its cationic derivative (Pc-2) were characterized by standard spectroscopic techniques, namely; FT-IR, 1H and [Formula: see text]C NMR, UV-Vis and MALDI-TOF, and by elemental analysis. The photophysical and photochemical properties were evaluated in DMSO for the non-ionic Pc-1 and in both DMSO and water for the cationic Pc-2.

Improving the non-linear absorption properties of graphene materials is valuable for optical limiting applications. We report the non-linear optical characteristics of new hybrid materials formed by the non-covalent functionalisation of graphene nanoplatelets (GNs) with pyrene-conjugated Zn(II) phthalocyanines and pyrene-conjugated Zn(II) azaphthalocyanines. The GN–pyrene-conjugated Zn(II) phthalocyanine hybrid (GPc) shows a promising change from the two-photon absorption behaviour of GNs to three-photon absorption, the first such example in a graphene based hybrid system under nanosecond pulse excitation. Fluorescence and transient absorption spectroscopies are employed to describe the non-linear optical phenomena of the prepared hybrid materials. The GPc hybrid exhibits a low optical limiting threshold induced by three-photon absorption and a favourable linear transmittance (above 90%). The GN–pyrene-conjugated azaphthalocyanine hybrid (GAzaPc) also shows promising non-linear optical coefficients. A unique optical limiting performance (80% reduction in intensity) is achieved throughout the experimental range of excitation intensities. Our research offers a way to design hybrid material structures with a large effective three-photon absorption coefficient and nearly constant optical limitation across a wide intensity range with 92% linear transmittance, which would be highly useful in non-linear photonic applications.

The excellent surface catalytic potential of Fe3O4–OSO3H is utilized in the synthesis of symmetrically and unsymmetrically substituted urea derivatives via transamidation reactions. The scope of the surface catalysis is further extended in transamidation reactions of cyclic and acyclic amide derivatives, and in the amidation of fatty acids. In both transamidation and amidation reactions, the catalyst is reusable up to five times without significant loss in its activity.

The design and synthesis with full structural utilization of a new type of nonlinear photonic material, Zinc(II) phthalocyanine macrocycle (Pc-pyrene), bearing binary oriented (up/down) pyrene units is reported. The novel pyrene-based macrocycle has been successfully obtained in high yield upon coupling multiple azido pyrene derivatives on a previously fabri-cated alkynyl-substituted macrocyclic platform (Pc1) via multiple tandem Cu(I)-catalysed azide-alkyne cycloaddition (CuAAC) reactions. The ultrafast nonlinear optical characteristics of both Pc1 and Pc-pyrene have been investigated in solution using a near-infrared femtosecond pulsed laser. The femtosecond Z-scan results reveal a low optical limiting threshold and a good set of figures of merit that make these macrocycles feasible for optical limiting as well as switching applications. In a major breakthrough, ultrafast laser-induced deformations in Pc-pyrene-embedded PMMA films results in a very large enhancement of the three-photon absorption coefficient at 800 nm by up to ~105 times that of Pc solutions. Furthermore, the deformed Pc-pyrene PMMA films having the advantage of flexibility and possess an excellent optical limiting threshold (0.0018 J/cm2), much lower than various previously reported values, which enables them to be one of the best optical limiters.

Readily available, non-toxic, biodegradable oleic acid was found to catalyse 4H-chromene derivatives syntheses in good yields in a water medium. A facile domino one-pot protocol was also developed for the oleic acid catalysed pyrimidine-fused heterocycle synthesis by pseudo three-component, three-component and four-component reactions. All the products were obtained in good to excellent yields. Oleic acid catalysis was further extended to the synthesis of curcumin based bioactive molecules.

Increased expression of efflux transport proteins confers the Multi Drug Resistant (MDR) phenotype to drug resistant bacteria, which can be mitigated by efflux pump inhibitors (EPI). EPI's have the dual advantage of restoring efficacy of antibiotics and retarding the evolution of drug resistant mutants. In this study, 17 heterocyclic derivatives synthesized by a polyethylenimine (PEI) catalyzed one-pot protocol were evaluated for their EPI potential. Based on in silico studies and in vitro studies, 5 benzochromene (BC) based compounds (among 17 heterocyclic derivatives), were observed to significantly potentiate the effect of ciprofloxacin (CPX) and displayed a best modulation factor of 32, against the NorA overexpressed mutant SA-1199B. Toxicity analyses using the zebrafish model showed that, from all the benzochromene compounds evaluated, BC9 exhibited low toxicity. BC9 inhibited the NorA efflux pump at a minimum effective concentration (MEC) of 2 μg ml−1 (4.03 μM) and even at subinhibitory concentrations, and it was effective in reversing the CPX MIC of both the ATCC strain and a clinical isolate of MRSA by 128 and 4 fold respectively. Our results show that benzochromene derivative BC9 is a highly specific NorA inhibitor that can be employed to mitigate MDR strains of S. aureus that overexpress the NorA efflux pump.

Fe 3 O 4 -OSO 3 H was identified as an efficient reusable catalyst for the facile synthesis of diarylmethyl indole derivatives under neat condition by C–C bond forming reaction. Fe 3 O 4 -OSO 3 H catalysis was further extended to C–N bond forming reactions and for the synthesis of spermicidal 3,3′-di(indolyl)oxindole derivative. All the products were obtained in good to excellent yields.

Copper(II) chloride is utilized to carry out ligand-free one-pot synthesis of triarylmethane derivatives in moderate to good yields. Copper(II) chloride also facilitated the transformation of both bis(indolyl)methane and leuco base to the corresponding triarylmethane derivatives by aryl group transfer. Based on the observed aryl transfer, an easy access to triarylmethane derivatives is devised by treating an equimolar mixture of bis(indolyl)methane and leuco base with indole or N,N-dimethylaniline in the presence of CuCl2.

Oleic acid was identified to catalyse bis(indolyl)methane and densely functionalized 4H-chromene, spirooxindole and spiro[indoline-3,4′-pyrano[2,3-c]pyrazole] derivative synthesis in good to excellent yields. The synergy between Bronsted acidity and surfactant ability of naturally available oleic acid was exploited to carry out the aforementioned transformations.

Hyperbranched polyethylenimine (HPEI), an amine rich polymer, has been used as a colorimetric probe for selective sensing of multiple metal ions (Cu2+, Co2+ and Fe2+) with clearly distinguishable color in aqueous solution. The selective coordination of Cu2+ with the chelating amines of HPEI induced a visible color change from colorless to blue across a wide pH range (pH 4.0 to 10.0). Other metal ions did not show any significant color change. Interestingly, the addition of Co2+ and Fe2+ into HPEI in the presence of silver ions (Ag+) leads to the formation of strong yellow and brown colors, respectively. The control studies suggest that Co2+ and Fe2+ undergo oxidation and reduce the silver ions into silver nanoparticles (AgNPs). The strong surface plasmon resonance (SPR) vibration of the AgNPs was responsible for the yellow/brown color. UV-visible studies showed a strong absorption peak at 400 nm for Co2+ and a broad absorption with λmax at 420 nm for Fe2+. HR-TEM studies confirmed more uniform spherical AgNPs for Co2+ with HPEI–Ag+ and polydisperse AgNP aggregates for Fe2+. The limit of detection of the HPEI probe for Cu2+ is 0.25 μg L−1 and those of the HPEI–Ag+ probe for Co2+ and Fe2+ are 40 and 30 μg L−1, respectively. The practical application of the HPEI probe for selective sensing of multiple metal ions with distinguishable colors has been demonstrated on Whatman filter paper. Thus, simple commercially available HPEI has been successfully used for the selective colorimetric sensing of biologically important Cu2+, Co2+ and Fe2+ metal ions in aqueous medium.

Hyperbranched polyethylenimine derivatives were successfully employed as catalyst in the Henry reaction. The nitroalcohol products were obtained in excellent yields within short reaction times. A one-pot synthesis of β-nitrostyrenes was developed by using ZnCl2 along with hyperbranched polyethylenimine derivatives.

Anhydrous ZnCl2 mediated convenient, one-pot synthesis of 3-arylmethyl and diarylmethyl indoles was accomplished in good yields. Under reaction condition, in situ formation of kinetically stable bis(indolyl)methane product was identified. Its subsequent conversion to the thermodynamically stable 3-diarylmethyl indole at elevated temperature and pressure was confirmed by carrying out pressure tube reaction with bis(indolyl)methane.

Three-component Betti reaction was carried out in the environmentally benign, inexpensive, non-toxic solvent glycerol. Even in the absence of a catalyst, the reaction went completion with an unprecedented high rate and the expected Betti bases were obtained in up to 91% yield. The reaction works well for representative cyclic, acyclic, aliphatic, and aromatic amines and aldehydes. A benzoxanthene was also prepared in 93% yield following the same methodology with 20 mol% methanesulfonic acid catalyst.

The title compounds are prepared by a facile domino one-pot protocol involving pseudo three-component, three-component or four-component reactions.

The developed method allows for the preparation of functionalized 4H-chromene, spirooxindole, spiro[indoline-3,4′-pyrano[2,3-c]pyrazole], and bis(indolyl)methane derivatives.

Hyperbranched polyethylenimine derivatives were successfully employed as catalyst in the Henry reaction. The nitroalcohol products were obtained in excellent yields within short reaction times. A one-pot synthesis of β-nitrostyrenes was developed by using ZnCl2 along with hyperbranched polyethylenimine derivatives.

Glycerol is described as useful solvent for the rapid one-pot synthesis of Betti bases without the need for any catalyst.