Soujanya Tirapattur, S Yarasi

• Doctor of Philosophy
• Senior Researcher at Indian Institute of Chemical Technology

Identification and characterization of biproducts/ impurities present in agrochemicals are critical in view of their efficacy and safety towards public health. We herein present our study on identification and characterization of an impurity, 5‐chloro‐2‐cyano‐N,N‐dimethyl‐4‐p‐tolylimidazole‐1‐sulfonamide (2) present in the fungicide, “cyazofamid”....

One of the major challenges in drug development is having acceptable levels of efficacy and safety throughout all the phases of clinical trials followed by the successful launch in the market. While there are many factors such as molecular properties, toxicity parameters, mechanism of action at the target site, etc. that regulates the therapeutic a...

A one pot multicomponent protocol to acess spirooxazolidine‐2‐thiones and spirooxothiolane‐2‐imines starting from isatin, phenyl acetylene and isothiocyanates has been accomplished. The reactivity of ambident nucleophilic sites: nitrogen and sulfur in an isothiocyanate is explored and an attempt has been made to fine tune the reaction parameters fo...

The design of an efficient photocatalytic system with a capability of effective photon conversion for hydrogen evolution is highly challenging. Herein, we report the first example of phenanthroline based ruthenium complexes (PRC1-3) embedded nanostructured hierarchical porous TiO2 composites (HPT) that showed impressive H2 evolution reaction (HER)...

The constant increase in greenhouse gases, namely CH4, N2O, and CO2, in the atmosphere is the major cause of the global warming phenomenon. An economical and sustainable CO2 capture technology will enable the industries to use fossil-based fuel while restraining the CO2 emissions into the atmosphere. Among different methods reported for the removal...

The present study evaluates the CO2 adsorption capacity of functionalized rutile TiO2 (110), using the density functional theory and ab initio molecular dynamics simulations. The defect-free TiO2 surface is functionalized (f-TiO2) with alkanolamines (AKAs) namely, monoethanolamine (MEA), 3-aminopropanol (3AP); and amino acids (AAs) glycine (GLY), ...

In an effort to replace the widely used ruthenium metal complexes with low-cost, earth abundant iron complexes as photosensitizers for dye-sensitized solar cell (DSSC) applications, herein we report the computational design of heteroleptic iron complexes (FC1–3) coordinated with benzimidazole-phenylcarbene (C^N) ligands. DFT and TDDFT calculations...

Porphyrins dyes are known as promising sensitizers for dye sensitized solar cell (DSC) devices because of their intrinsic features with maximum reported light-to-electricity conversion efficiency of about 12%. Our objective in this study is to rationally design new porphyin sensitizers with enhanced photovoltaic (PV) properties, Voc (open-circuit v...

Herein, for the first time we report the synthesis of a series of compositionally tunable Zr doped novel KNb(Zr)O3 perovskites using green and facile methodology and their superior photocatalytic activities towards photo-induced hydrogen production and dye degradation. The substitutional doping of Zr(IV) in place of Nb(V) leads to decrease in the e...

We have designed and synthesized two new ligands based on N-heteroleptic/phenyl carbene (NH-phenyl C) i.e., 1-benzyl-2-(3,5-bis(trifluoromethyl)phenyl)-1H-benzo[d]imidazole (L1) and 3-(1-benzyl-1H-benzol-2-yl)-10-hexyl-10-H-phenothiazene (L2), used as ancillary ligands to heteroleptic Ru(II) complexes for dye-sensitized solar cells. Both NCS groups...

The current study reports one-step synthesis and gelation properties of cyclohexane based bis (acylsemicarbazide) gelators with additional -NH group incorporated into urea moieties and carrying hydrophobic chains of varying length (C8-C18). The gels exhibited thermo reversibility and could be tuned in the presence of anions at different concentrati...

Zeolitic imidazolate frameworks (ZIFs) represent the class of metal-organic frameworks (MOFs) that possess high porosity, large surface area, exceptional thermal, and chemical stability. Because of these properties, ZIFs are being employed extensively in gas separation and selective CO2 adsorption. We have chosen the structural modification approac...

We have designed and synthesized heteroleptic Ru(II) complexes having pyridine-benzimidazole ligand (PYBI) for dye-sensitized solar cell (DSSC) applications. The PYBI ligands has major advantage by having flexibility to introduce proper substituents at readily available four positions through molecular engineering (chart 1) compared to other ancill...

First principles calculations based on density functional theory (DFT) have been performed to design a new set of donor-corrole-bridge-acceptor type systems based on the gallium corroles for dye-sensitized solar cell applications. The design strategy for these systems is based on the benchmark studies done on the experimentally tested aluminum, gal...

The cation binding strength of calix[4]pyrroles in the gas phase has been evaluated by computational studies and further substantiated by ESI mass spectrometry experiments. The DFT optimized geometries of [CP + X](+) complexes are found to be stable in a 1,3-alternate conformation through cation-π interactions and interestingly CPs are found to be...

Three new sterically demanding unsymmetrical zinc phthalocyanines have been designed and synthesized as sensitizers for dye-sensitized solar cells. All three unsymmetrical phthalocyanines have been completely characterized by elemental analyses, mass spectrometry, FT-IR, 1H NMR, UV–Visible, and fluorescence (steady-state and life-time) spectroscopi...

Molecular triads based on bis-porphyrin-anthraquinone having azomethine-bridge at the pyrrole-β position have been designed and synthesized. Both free-base AQ-(H2)2 and zinc AQ-(Zn)2 triads are characterized by elemental analysis, MALDI-MS, 1H-NMR, UV-Visible and fluorescence spectroscopy (steady-state and time-resolved) as well as electrochemical...

Molecular triads based on bis(porphyrin)−anthraquinone having azomethine bridge at the pyrrole-β position have been designed and synthesized. Both free-base AQ-(H 2) 2 and zinc AQ-(Zn) 2 triads are characterized by elemental analysis, MALDI-MS, 1 H NMR, UV−visible, and fluorescence spectroscopy (steady-state and time-resolved) as well as electroche...

Oxidative difunctionalisation of chromene double bond has been studied in alcoholic solvent medium in presence of Iodobenzene diacetate (IBD) and as well as N-Chlorosucccinimide (NCS). While addition occurs the double bond in the NCS mediated conditions, an unusual 1,2-migration of amino group occurs in IBD mediated protocol.

C-3 symmetric chiral trimethylsumanene was enantioselectively synthesized through Pd-catalyzed syn-selective cyclotrimerization of an enantiomerically pure iodonorbomenone, ring-opening/closing olefin metathesis, and oxidative aromatization where the sp(3) stereogenic center was transmitted to the bowl chirality. Chiral HPLC analysis/resolution of...

A new extended thermo-stable high molar extinction coefficient bipyridyl ruthenium(II) complex "cis-Ru(4,4'-bis(3,5-di-tert-butylphenyl)-2,2'- bipyridine)(Ln)(NCS)2 H101", where Ln = 4,4'-dicarboxylic acid-2,2'-bipyridine; was synthesized and characterized by 1H-NMR, FT-IR and ESI-MASS spectroscopes. The H101 sensitized solar cell constructed with...

Comprehension of the basic concepts for the design of systems for CO2 adsorption is imperative for increasing interest in technology for CO2 capture from the effluents. The efficacy of 20 naturally occurring amino acids (AAs) is demonstrated as the most potent CO2 capturing agents in the process of chemical absorption and physisorption through a sy...

We have designed a new triphenylamine–phthalocyanine based sensitizer (Pc-Org-1) having three bulky triphenylamine groups, which acts as donor and two carboxyl groups, which acts as acceptor as well as servers to graft onto nanocrystalline TiO2. The new sensitizer was fully characterized by CHN, Mass, UV–Vis, fluorescence spectroscopies and cyclic...

Two new heteroleptic ruthenium(II) photosensitizers that contains 2,2';6,2''-terpyridine with extended π-conjugation with donor groups, a 4,4'-dicarboxylic acid-2,2'-bipyridine anchoring ligand and a thiocyanate ligand have been designed, synthesized and fully characterized by CHN, mass spectrometry, UV-vis and fluorescence spectroscopies and cycli...

A new high molar extinction coefficient organic-ruthenium(II) polypyridyl complex sensitizer (RD-Cou) that contains 2,2′,6,6′-tetramethyl-9-thiophene-2-yl-2,3,5,6,6a,11c-hexahydro1H,4H-11oxa-3a-aza-benzoanthracene-10-one as extended π-conjugation of ancillary bipyridine ligand, 4,4′-dicaboxy-2,2′6′,2′′-bipyridine, and a thiocyanate ligand in its mo...

Two new ruthenium(II) mixed ligand terpyridine complexes, “Ru(Htcterpy)(NCS)(L1) (N(C4H9)4), mLBD1” and Ru(Htcterpy)(NCS)(L2)(N(C4H9)4), mLBD2 were synthesized and fully characterized by UV-Vis, emission, cyclic voltammogram, and other spectroscopic means, and the structures of the compounds are confirmed by 1H-NMR, ESI-MASS, and FT-IR spectroscope...

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

To explore the origin of the differences in UV photochemistry of uracil (RNA) and thymine (DNA) nucleobases, we have measured the UV resonance Raman spectra of uracil in aqueous solution at wavelengths throughout the lowest-energy absorption band and analyzed the resulting resonance Raman excitation profiles and absorption spectra using a time-depe...

Two efficient heteroleptic ruthenium (II) complexes, cisdi(thiocyanato)(4,4'-dicarboxylic acid-2,2'-bipyridine)(4,4'-bis(2(3,5-di tert- butylphenyl) ethenyl)-2,2'-bipyridine)ruthenium (II) (HRD-1) and cis-di(thiocyanato)(4,4'-dicarboxylicacid-2,2'-bipyridine)(4,4'-bis(2-(2,3,5-trimethylphenyl)ethenyl)-2,2'-bipyridine) ruthenium (II) (HRD-2) were sy...

Theoretical investigations have been carried out at B3LYP/6-311++G** level of theory to study the binding interaction of various metal ions, Li+, Na+ and K+ with dehydroannulene systems. The present study reveals that alkali metal ions bind strongly to dehydroannulenes and the passage through the central cavity is controlled by the size of metal io...

The computational study explores the electronic fine tuning of the exocyclic C-C single bond length in tetrahedranyl tetrahedrane as a function of various substituents. The factors which determine the bond lengths and bond strengths are examined by using the EDA method.

A series of diastereomeric 4S,5S,6R/S-tetrahydropyrano- and 3S,4S,5R/S-tetrahydrofuranochromenylamine derivatives (a/b isomers; 1-26) has been studied under electron ionization (EI) and chemical ionization (CI) conditions. The EI mass spectra of all diastereomeric compounds show two characteristic fragment ions, of which one is formed by retro-Diel...

Density functional theory (DFT) calculations using the B3LYP/6-311G(d,p) basis set of ten isotopomers of thymine and four isotopomers of uracil, including the natural abundance isotopomers, are reported. Comparison of the calculated wavenumber shifts upon hydrogen, carbon and nitrogen isotopic substitution with those from experimental Raman and inf...

To explore the excited-state structural dynamics of thymine, a DNA nucleobase, we measured the resonance Raman spectra of thymine in aqueous solution at wavelengths throughout the lowest-energy absorption band. Self-consistent analysis of the resulting resonance Raman excitation profiles and absorption spectrum using a time-dependent wave packet fo...

Theoretical calculations by means of density functional theory (DFT) at the B3LYP/6-31G(d) level have been performed to elucidate the antioxidant mechanism of 1,3-dihydro-1-methyl-2H-imidazole-2-selenol (MSeI) at the molecular level. The present detailed computational study of individual steps of the mechanism provides energetics and structures of...

Diastereomeric conduramine derivatives, i.e., (1R,2S,3R/S,6S)-6-(N-carbomethoxyamino) 1,2-O-isopropylidenecyclohex-4-ene-1,2,3-triol (1 and 2) and their O-acetyl derivatives (3 and 4), were studied using gas chromatography (GC) with electron ionization (EI) and chemical ionization (CI). The EI mass spectra of diastereomeric pairs show consistent di...

B3LYP/6-311+G** calculations were performed systematically on 1,2 (syn) and 1,3 (anti) tautomeric forms of oxa- and thia- core-modified porphyrin isomers, which resulted in a total of 86 structures. The structural and energetic variation in all the isomers were analyzed. In corrphycene, hemiporphycene and porphycene the Z forms are more stable comp...

Molecular beacons (MB) are becoming more common as sequence-selective detectors of nucleic acids. Although they can easily detect single-base mismatches, they have never been used to directly detect DNA or RNA damage. To measure the degree of ultraviolet (UV) light damage in oligonucleotides, we report a novel MB approach for general detection of p...

We present Raman spectra of five sunscreen active ingredients in 10 solvents. Shifts in the UV absorption maxima and the CO Raman mode wavenumber are observed for some of the sunscreens as a function of solvent. Correlations between the observed wavenumber shifts and solvent properties indicate that hydrogen bonding is a key interaction between sun...

Geometry optimizations of the ground state of oligofluorenes were carried out at the restricted Hartree – Fock level (RHF/6-31G*). This was followed by the use of the restricted configuration interaction/singles (RCIS/6-31G*) approach to optimize the geometry of the lowest (singlet) excited state (S 1). It is found that these molecules are nonplana...

The UV–Vis absorption spectra and the luminescence properties of poly(N-octyl-2,7-carbazole) (POC) and poly(N-octyl-2,7-carbazole-alt-9,9-dioctyl-2,7-fluorene) PCF have been investigated in solution and in the solid state (thin films). No aggregate and/or excimer formation has been detected in these polymeric systems. From time-resolved fluorescenc...

The optical and photophysical properties of fluorene-based polyesters in solution and in the solid state (thin films) are reported. The red-shifted emission bands observed in the photoluminescence spectra of the thin films are rationalized in terms of stronger π−π intermolecular interactions due to the closeness of the molecules (molecular packing)...

A detailed analysis of the optical and photophysical properties of 2,7-bis(phenylene)-9,9-dioctylfluorene (PFP), 2,7-bis(biphenylene)-9,9-dioctylfluorene (BPFBP), 2,7-bis(2-thienyl)-9,9-dioctylfluorene (TFT), and 2,7-bis(2,2\-bithien-5-yl)-9,9-dioctylfluorene (BTFBT) in various environments are reported. The optical properties of the free molecules...

Photoresponsive molecular receptors based on the photophysical properties of the pyrene chromophore were designed to exhibit tunable fluorescence emission upon binding of transition-metal ions.

Substituted naphthylacrylates, 1-3, not showing rotamerism have been synthesized with a view to study photochemical E (trans)-->Z (cis) isomerization. Photostationary state composition of the isomers upon direct excitation, triplet sensitized isomerization, quantum yield of isomerization, and steady state and time-resolved fluorescence behavior hav...

The design and synthesis of two conjugated pyrene-2,2′-bipyridine linear rods is described. Zn(II) ion complexation allows the formation of a highly polar emissive excited state through efficient photoinduced intramolecular charge transfer.

A series of tunable fluorophores combining the pyrene nucleus and the 2,2′-bipyridine ligand unit are presented. They were designed to display luminescence tuning upon metal ion complexation. The effects are strongly affected by the nature of the covalent bridge linking the two subunits. The intensity, the color, but also the lifetime of the lumine...

Two fluorescent pyrene derivatives, I and II, are reported in which the aromatic ring is connected to the 2,2'-bipyridine (bpy) complexing unit via a single C−C bond. Compound I contains one bpy moiety at the 1 position of the pyrene nucleus while II bears two bpy moieties linked to the 1 and 6 vertexes. The solvent-polarity dependence of the fluor...

One-way cis to trans photoisomerization is achieved in styrylnaphthalene derivative (3) by suppressing the trans to cis isomerization with the use of suitable substituents and solvents.

The potential of 4-aminophthalimide (AP) and its derivatives as fluorescence probes for organized media is highlighted. The fluorescence response of AP, as measured from the position of the fluorescence maximum, fluorescence intensity and lifetime, is highly sensitive to the polarity of the medium. The sensitivity of the fluorescence parameters is...

Photophysical behavior of 4-aminophthalimide and its N,N-dimethyl derivative is studied in a series of solvents. A comparison of the fluorescence properties of the two compounds reveals that they behave quite differently despite their structural similarity. The efficient nonradiative decay of the dimethyl derivative in polar media is interpreted in...

Excited-state dipole moments of a set of Coumarin dyes extensively used in laser applications have been determined for the first time, employing a solvatochromic procedure utilising the microscopic solvent polarity parameter, ENT. Our results are expected to be quite reliable in view of the fact that the correlation of the solvatochromic Stokes shi...

The twisted intramolecular charge transfer phenomenon in p-(N,N-dimethylamino)benzonitrile has been studied using Austin model 1 (AM1) semi-empirical calculations. A detailed picture of the twisting process is obtained by calculation of the ground and excited state profiles as a function of twist angles. The effect of solvent on the energetics is o...

Lipids that are covalently labeled with the 7-nitrobenz-2-oxa-1,3-diazol-4-yl (NBD) group are widely used as fluorescent analogues of native lipids in model and biological membranes to study a variety of processes. We have recently shown that one such NBD labeled lipid, NBD-PE, in which the NBD label is covalently attached to the headgroup of a pho...

The complexation between 4-aminophthalimide and cyclodextrin has been investigated in aqueous solution using steady-state and time-resolved fluorescence techniques. While 1:1 complex formation with α or Î-cyclodextrin is evident from the presence of the isosbestic point in absorption and analysis of fluorescence spectral data, the binding is rathe...

Steady state and time-resolved studies on the fluorescence of 4-aminophthalimide (AP) in aqueous β-cyclodextrin (CD) solutions are reported. A blue shift of the fluorescence maximum, enhancement of the fluorescence quantum yield and increase in the lifetime of the emitting intramolecular charge-transfer state are observed on addition of CD to an aq...