Chinnadurai Satheeshkumar

Influence of triazole dendritic additives in electrolytes on dye-sensitized solar cell (DSSC) performance

Novel triazole dendritic molecules bearing dimethyl isophthalate surface group are synthesized. The enhancement of triazole and carboxylate groups in the dendritic structures significantly alter the absorption, electrochemical and DSSCs behaviors. With dendritic additive DSSCs cell exhibited higher Voc values and power conversion efficiency (η) in I−/I3−redox couple under simulated AM 1.5 at 40 mW cm−2.

Synthesis of triazole dendrimers with a dimethyl isophthalate surface group and their application to dye-sensitized solar cells

Dendritic architectures with 1,2,3-triazole as the building unit and dimethyl isophthalate as the surface group are synthesized through a convergent approach employing click chemistry and tested for their application in dye-sensitized solar cells (DSSCs). The studies revealed that the presence of triazole and isophthalate groups in dendritic structures significantly altered the absorption, electrochemical and DSSC behaviors. In DSSCs, the dendritic structures exhibited higher Voc values and higher power conversion efficiency (η) in the I−/I3− redox couple under simulated conditions at 40 mW cm−2.

Enhanced performance of dye-sensitized solar cell using triazole based phenothiazine dendrimers as additives

Phenothiazine dendritic architectures with 1,2,3-triazole as a bridging unit are synthesized through a convergent approach using click chemistry and when used as additives in dye-sensitized solar cells (DSSCs) show increased efficiency in solar energy harvesting systems. The presence of a greater number of phenothiazine and triazole units increased the molar absorption coefficient and fluorescence quantum yields. In DSSCs, the redox couple doped with first generation triazole based phenothiazine dendrimers showed a higher Voc voltage through the suppression of back electron transfer and exhibited a better power conversion efficiency (η) of 8.6% under 70 mW cm−2 irradiation than the zeroth generation dendrimers.

Synthesis and antimicrobial activity of some novel dicationic sulphonophanes

The synthesis of some novel imidazole-based dicationic sulfonophanes incorporating various spacer units is described. All the sulphonophanes exhibit good antibacterial and antifungal activity against five bacterial strains Bacillus subtilis, Staphylococcus aureus, Vibrio cholera, Escherichia coli, Proteus vulgaris and human pathogenic fungus Candida albicans.

Synthesis and electronic properties of N-heterocyclic carbene-containing conducting polymers with coinage metals

Following the recent development of functional materials based on metal-containing conducting polymers, we designed and synthesized a series of bithiophene based N-heterocyclic carbene (NHC) conducting polymers containing coinage metals (Cu, Ag, and Au). Absorption spectroscopy, NMR spectroscopy, cyclic voltammetry, and X-ray photoelectron spectroscopy (XPS) were used to analyze the monomers and the polymer thin films. The peak currents of the electrodeposited films on Pt-button electrodes increased proportionally with the scan rate, exhibiting the stability of the polymer thin films. Remarkably, in the electrochemical studies of the coinage metal complexes, the redox potential of Cu+/Cu2+ perfectly matched with the redox wave of quaterthiophene moieties of the polymer backbone. However, the redox potential of Ag/Ag+ did not match with the redox potential of the polymer backbone. During the oxidation process in the spectroelectrochemical studies, the conducting coinage metallopolymers exhibited a drastic color change from orange (reduced form) to dark green (oxidized form), and they can be envisioned in the applications of electrochromic materials.

Tuning Sensory Properties of Triazole-Conjugated Spiropyrans: Metal-Ion Selectivity and Paper-Based Colorimetric Detection of Cyanide

Tuning the sensing properties of spiropyrans (SPs), which are one of the photochromic molecules useful for colorimetric sensing, is important for efficient analysis, but their synthetic modification is not always simple. Herein, we introduce an alkyne-functionalized SP, the modification of which would be easily achieved via Cu-catalyzed azide-alkyne cycloaddition (“click reaction”). The alkyne-SP was conjugated with a bis(triethylene glycol)-benzyl group (EG-BtSP) or a simple benzyl group (BtSP), forming a triazole linkage from the click reaction. The effects of auxiliary groups to SP were tested on metal-ion sensing and cyanide detection. We found that EG-BtSP was more Ca2+-sensitive than BtSP in acetonitrile, which were thoroughly examined by a continuous variation method (Job plot) and UV-VIS titrations, followed by non-linear regression analysis. Although both SPs showed similar, selective responses to cyanide in a water/acetonitrile co-solvent, only EG-BtSP showed a dramatic color change when fabricated on paper, highlighting the important contributions of the auxiliary groups.

Synthesis and application of stilbenoid phenothiazine dendrimers as additives for dye-sensitized solar cells

Stilbenoid dendrimers with phenothiazine as a surface group were synthesized in good yields by the Heck and Horner–Wadsworth–Emmons coupling reaction and characterized by spectral and analytical data. Various core units such as trimethylbenzene, pyridine, and triphenylamine with phenothiazine as the surface unit were employed for the synthesis of dendrimers. The photophysical properties of the dendrimers reveal that as the generation increases the light absorption ability also increases. Furthermore, as the generation increases the absorption maxima show a hypsochromic shift for the n–π* transition and a bathochromic shift for the π–π* transition. However, the fluorescence emission in general increases as the dendrimer generation increases. When the synthesized stilbenoid dendrimers are utilized as an additive in the redox couple (I−/I3−) of a Dye Sensitized Solar Cell (DSSC), the solar energy conversion efficiency increases with an increase in generation and reaches a maximum of 7.3% with the higher generation dendrimer 10.

Synthesis, anti-microbial activity and molecular docking studies on triazolylcoumarin derivatives

AbstractA series of triazolylcoumarins was synthesized by the cycloaddition of acetylenic derivatives to azide in the presence of Cu(I) catalyst at room temperature. All the synthesized compounds were evaluated for their anti-microbial activity against Gram-positive (B. subtilis and S. aureus), Gram-negative bacteria (K. pneumonia and P. vulgaris) and human pathogenic fungi (C. tropicalis and C. krusei), with tetracycline and fluconazole as standards for anti-microbial and anti-fungal activity. Triazolylcoumarins exhibit anti-microbial activity against all the tested pathogens, which is further supported by molecular docking studies. Graphical AbstractA series of triazolylcoumarins was synthesized using click chemistry approach. All the triazolylcoumarin compounds were evaluated for their anti-microbial activity against Gram-positive, Gram-negative bacteria and human pathogenic fungi, with tetracycline and fluconazole as standards as supported by molecular docking studies.

Thiol–ene photopolymerization of vinyl-functionalized metal–organic frameworks towards mixed-matrix membranes

We developed a facile methodology for fabricating a free-standing mixed-matrix membrane (MMM) containing covalently incorporated metal–organic framework (MOF) particles up to 60 wt% by utilizing thiol–ene photopolymerization with the MOF consisting of vinyl functionality. Vinyl-functionalized UiO-66 (UiO-66-CHCH2) was synthesized from 2-vinyl-1,4-dicarboxylic acid with ZrCl4, and a free-standing MMM was readily produced by irradiation of a polymerization mixture containing UiO-66-CHCH2, poly(ethylene glycol) divinyl ether (PEO-250), pentaerythritol tetra(3-mercaptopropionate) (PETM), 2,2′-(ethylenedioxy)diethanethiol (EDDT), and 2,2-dimethoxy-2-phenylacetophenone (DMPA) as a photoradical initiator. Assorted analyses combining FTIR, thermogravimetric analysis, scanning electron microscopy, energy dispersive X-ray spectroscopy, and X-ray diffraction strongly supported the fact that the desired MMM containing well-dispersed UiO-66-CHCH2 particles was successfully produced by C–S bond formation, which provided strong union of the MOF with the polymer matrix without interfacial voids. The produced MMM was highly flexible and showed improved mechanical properties as compared to the pristine polymeric membrane, indicating that the covalently immobilized UiO-66-CHCH2 particles were homogeneously distributed in the polymer matrix. Gas permeability across the MMM was significantly enhanced compared with the pristine polymeric membrane as diffusion of the gas molecules was facilitated in the porous space in the MOF.