Revealing the Role of Electronic Effect to Modulate the Photophysics and Z-Scan Responses of -Locked GFP Chromophores.

Three novel core green fluorescent protein (GFP) chromophore analogues, based on a doubly locked conformation and variable electronic effects by replacing one hydrogen with bromine, iodine, and methyl, respectively, have been synthesized to modulate the push-pull effect. These chromophores exhibited intramolecular H-bonding, as evidenced by single-crystal X-ray and H NMR studies. The fluorescence quantum yields (ϕ) of all of the chromophores were found to be more than an order of magnitude higher (∼0.

Ni(II) and Pd(II) complexes of a new redox-active pentadentate azo-appended 2-aminophenol ligand: Pd(II)-assisted intraligand cyclization forms a phenoxazinyl ring.

Square planar complexes of Ni(II) and Pd(II) of a new redox-active pentadentate azo-appended 2-aminophenol ligand (HL = ,'-bis(2-hydroxy-3,5-di--butylphenyl)-2,2'-diamino--azobenzene) in three accessible redox levels [amidophenolate(2-), semiquinonate(1-) π radical, and quinone(0)] were synthesized. The coordinated HL(3-) ligand provides four donor sites [two N(iminophenolates), an N'(azo), and an O(phenolate)], while the phenolic OH group remains free in the three complexes. Cyclic voltammetry on complex [Ni(L)] 1 and its corresponding Pd(II) analogue [Pd(L)] 2 in CHCl displayed three redox responses (two oxidative at = 0.

Understanding the gelation properties of the fluorophenyl glycosides of arabinoside gelators: experimental and theoretical studies.

In supramolecular gelation, fluorinated gelators are important due to the unique properties displayed by these compounds that arise out of the presence of fluorine atoms. Generally, incorporation of fluorine leads to higher mechanical strength of the gels compared to their non-fluorinated counterparts and this property is enhanced with increasing the number of fluorine atoms. Herein, we show that the incorporation of fluorine into the phenyl ring of phenyl arabinoside allows the molecule to act as a gelator, unlike the non-fluorinated compound.

Phenoxazinyl Zn(II) diradical complex formed redox-driven cyclization of a 2-aminophenol-based NO ligand. Isolation of the modified N ligand radical and its Ni(II) complex.

Aerobic reaction between the pyridine-2-carboxamide-2-aminophenol NO ligand (HL) and Zn(ClO)·6HO in CHCN affords an N phenoxazinylate coordinated Zn(II) complex; its diradical electronic structure [Zn{(L*)˙}] has been elucidated from redox, spectroscopic (UV-VIS and EPR), and magnetic measurements and DFT calculations. Isolation and characterization of the metal-assisted redox-driven modified N ligand as a radical cation (HL*)˙ and its Ni(II)-diradical complex [Ni{(L*)˙}] have also been achieved.

Bioactive metabolites of licorice and thyme as potential inhibitors of Cox1 enzyme of phytopathogens of L.: In-silico approaches.

Cytochrome c oxidase subunit 1 (Cox1), a key enzyme, has a crucial role in cellular respiration in eukaryotes and prokaryotes. Generally, respiratory inhibitors are considered one of the types of chemical pesticides. Thyme oil and licorice aqueous extract have been reported to have antifungal activities against fungal phytopathogens of L.

Acetoxy Group-Directed Regioselective C2 Alkenylation of Indoles via Pd-Ag Bimetallic Catalysis.

Regioselective C-H functionalizations of indoles reported to date with directing groups at C3 mainly rely on functional groups that are linked to the indole via C-C bonds. However, groups that are linked to the indole core by C-X linkages are also attractive due to the possibility of further modifications of the C-X bond. Herein, we report a 3-acetoxy directing group for the regioselective C2 alkenylation of indoles via a C-H activation-based, cross-dehydrogenative, oxidative Heck-type reaction.

Visible-light driven acetoxylation and dioxygenation of indoles electron donor-acceptor complexes.

A photoresponsive electron donor-acceptor (EDA) complex, formed by indole and hypervalent iodine such as diacetoxyiodobenzene (DAIB/PIDA, ), was detectable through absorption and emission spectroscopy. Irradiation of the EDA complex with visible light triggered photoinduced single electron transfer (SET) processes that were synthetically useful for the catalyst-free, regioselective acetylation of indoles. The photocatalytic reaction with excess DAIB was also used for the synthesis of isatins.

CuF/MeOH-Catalyzed N-Selective Chan-Lam Coupling of Hydantoins: Method and Mechanistic Insight.

An efficient and practical N-arylation of hydantoins with substituted aryl/heteroaryl boronic acids has been established, assisted by CuF/MeOH under the base and ligand-free conditions at room temperature and open air. The protocol is general, and various N-arylated hydantoins have been prepared in excellent yields with exclusive regioselectivity. The CuF/MeOH combination was explored further to furnish selective N-arylation of 5-fluorouracil nucleosides.

Organophotoredox-Catalyzed Cross-Dehydrogenative Sulfonamidation of Indoles and Other Heterocycles.

The visible light-triggered regioselective synthesis of 2-sulfonamidoindoles and other 2-sulfonamido heteroarenes is accomplished by the oxidative cross-dehydrogenative coupling of indoles (heteroarenes) with di--toluenesulfonamide or -aryl--toluenesulfonamides. The reaction was catalyzed by eosin-Y through a photoredox route. Detailed mechanistic studies based on control reactions, cyclic voltammetry, and fluorescence quenching have been reported for the elucidation of the mechanistic cycle and revealed that a nitrogen-centered radical is generated, followed by regioselective addition to the heteroarene.

Exploiting Coordination Behavior of 7-Azaindole for Mechanistic Investigation of Chan-Lam Coupling and Application to 7-Azaindole Based Pharmacophores.

Multiple spectroscopic techniques, along with single-crystal X-ray analysis, have been used to reveal the detailed structural and electronic information on reaction intermediates of a new copper(II)-DBU catalytic system for the N-arylation of 7-Azaindole. The reaction mixture of Chan-Lam cross-coupling yields two dimeric copper(II)-7-azaindole complexes, including one attached with DBU, prior to adding arylboronic acid and are confirmed structurally and spectroscopically. A suitable mechanism has been proposed using the dimeric copper(II) complex as a catalyst for the coupling reactions.

Stereoselective Routes to Hexahydropyrroloindoles and Tetrahydropyrroloquinolines from Activated Aziridines and Electron Deficient 3-Indoles.

An unprecedented and novel synthetic route to hexahydropyrrolo[2,3-]indoles bearing -contiguous stereocenters with excellent stereoselectivities (ee of >99%, dr of ≤99:1) has been disclosed that proceeds through the ring opening of activated aziridines with electron deficient 4-substituted indoles followed by a novel cyclization in a domino fashion, thereby obviating the use of 3-substituted indoles as the prerequisite nucleophile. Another efficient synthetic route to tetrahydropyrrolo[4,3,2-]quinolines in excellent yields (≤93%) and excellent enantioselectivity (ee of >99%) has been established via ring opening of activated aziridines with 4-bromo-1-methyl-1-indole at relatively higher temperatures followed by Cu(I)-catalyzed intramolecular C-N cyclization in the same pot. The stability and the formation of products at different temperatures are explained by computational studies.

Ni(II) complexes of a new tetradentate NN'N''O picolinoyl-1,2-phenylenediamide-phenolate redox-active ligand at different redox levels.

Three square planar nickel(II) complexes of a new asymmetric tetradentate redox-active ligand HL in its deprotonated form, at three redox levels, open-shell semiquinonate(1-) radical, quinone(0) and closed-shell dianion of its 2-aminophenolate part, have been synthesized. The coordinated ligand provides N (pyridine) and N' and N'' (carboxamide and 1,2-phenylenediamide, respectively) and O (phenolate) donor sites. Cyclic voltammetry on the parent complex [Ni(L)] 1 in CHCl established a three-membered electron-transfer series (oxidative response at = 0.

UV to NIR multistate electrochromism and electrofluorochromism in dibenzophenazine-arylamine derivatives.

An intriguing case of intramolecular and intervalence charge transfer-driven multistate electrochromism and electrofluorochromism in dibenzophenazin-(phenyl)methanone and arylamine-based redox-active donor-acceptor-donor molecules was elucidated. Tunable absorption from UV to NIR and on-off switching of fluorescence in a single-component all-organic molecular material by a subtle variation of electric potentials were demonstrated.

Memory of Chirality Concept in Asymmetric Intermolecular Michael Addition of α-Amino Ester Enolates to Enones and Nitroalkenes.

A highly stereoselective asymmetric intermolecular conjugate addition of α-amino ester derivatives to cyclic enones via the memory of chirality (MOC) concept in high yields with excellent diastereo- and enantioselectivity (dr >99:1, up to 99% ee) is reported. The applicability and the generality of the strategy was demonstrated by its further exploration to acyclic α,β-unsaturated ketone and aromatic nitroalkenes, resulting in the formation of δ-keto-α-amino ester derivative and γ-nitro-α-amino ester derivatives, respectively, with excellent ee and dr.

Low-spin [M(L)] and [M(L)] (M = Fe and Co) complexes of tridentate azo-containing pyridine/pyrazine amide ligands: structures, properties and redox potential correlations.

Using deprotonated forms of tridentate azo-containing pyridine-2-/pyrazine-2-carboxamide 2-[N-(2-phenylazo)carbamoyl]-pyridine/pyrazine, seven bis-ligand complexes of Fe/Co and Fe/Co have been synthesized. Molecular structures of six of them reveal that these six-coordinate complexes utilize all available donor sites of the ligands and assume MN(pyridine/pyrazine)N'(amide)N''(azo) coordination. Complexes of Fe and Co are diamagnetic and those of Fe and Co are paramagnetic (S = 1/2; room-temperature magnetic data and EPR spectra).

Bimolecular Photoinduced Electron Transfer in Static Quenching Regime: Illustration of Marcus Inversion in Micelle.

Ultrafast bimolecular photoinduced electron transfer (PET) between six coumarin dyes and four viologen molecules in the stern layer of sodium dodecyl sulfate micelle have been studied using femtosecond broadband transient absorption spectroscopy and femtosecond fluorescence up-conversion spectroscopy over a broad reaction exergonicity (ΔG). Emanating the formation of radical cation intermediates of viologen molecules using the transient absorption and the fast decay component of coumarins using the fluorescence up-conversion studies the forward bimolecular electron transfer rate (k) have been measured with high accuracy. The relationship of k with ΔG found to follow a Marcus type bell-shaped dependence with an inversion at -1.

Paraganglioma of the oropharynx.

Paraganglioma is a rare tumor in head and neck region. A 35 years male presented with huge swelling of tonsillar region occupying a large portion of oropharynx. Tumor had been dissected out transorally.

Clinico-epidemiological profile of chronic suppurative otitis media patients attending a tertiary care hospital.

The cross-sectional study was conducted to assess the clinico-epidemiological profile, perceptions and clinical profile of the chronic suppurative otitis media (CSOM) patients in a tertiary care hospital. A pretested questionnaire was used containing open questions and the patients were assessed clinically. Most patients (31.

Genomic instabilities in squamous cell carcinoma of head and neck from the Indian population.

Intrinsic genomic instability of an incipient tumor cell drives the development of cancer. In colorectal cancer, an inverse relationship between microsatellite instability (MIN) and chromosomal instability (CIN) has been reported. The relationship between MIN and CIN in head and neck squamous cell carcinoma (HNSCC) is uncertain.

Differential alterations of the genes in the CDKN2A-CCND1-CDK4-RB1 pathway are associated with the development of head and neck squamous cell carcinoma in Indian patients.

Purpose: The aim of this study was to analyse the alterations of the genes in the CDKN2A/CCND1/CDK4/RB1 pathway in the G1-S phase of the cell cycle during development of head and neck squamous cell carcinoma (HNSCC).

Methods: The alterations of these genes were analysed in 22 dysplastic lesions, 26 stage-I/II and 33 stage-III/IV HNSCC tumours of Indian patients.

Results: The alterations [mutation, hypermethylation, homozygous deletion and loss of heterozygosity/microsatellite size alteration (LOH/MA)] in the CDKN2A were found to be highest in 57% of the samples, followed by CCND1 amplification and LOH/MA at the RB1 locus in 14% and 8.

Differential deletions in 3p are associated with the development of head and neck squamous cell carcinoma in Indian patients.

In this study we performed detailed deletion mapping of two broad regions in the short arm (p) of chromosome 3 (i.e., 3p21.