Substituent Effect on Absorption and Fluorescence Properties of Thieno[3, 2-c]Pyridine Derivatives.

New substituted thieno[3,2-c]pyridine derivatives 5 were synthesized by the reaction of 3-bromo-4-chlorothieno[3,2-c]pyridine 1 with cyclic amine 2, which further on Suzuki reaction with boronic acids 4 converted to corresponding 3-arylthieno[3,2-c]pyridine 5. Substituent R3 has predominant effect on fluorescence properties of thienopyridines. However, the electron donor amine at C4 has no effect on fluorescence properties of thienopyridines. Graphical Abstract New thieno[3,2-c]pyridine derivatives were synthesized from 3-bromo-4-chlorothieno[3,2-c]pyridine and cyclic amines, which by on Suzuki reaction with boronic acids converted to corresponding 3-arylthieno[3,2-c]pyridine. Substituent R3 has predominant effect on fluorescence properties of thienopyridines. However, the electron donor amine at C4 has no effect on fluorescence properties of thienopyridines.

Synthesis and Study the Effect of Donor-Acceptor Substituent on Fluorescence Behavior of Thieno[3, 2-c]pyridine Derivatives.

4-Hetero-1-yl-2-bromothieno[3,2-c]pyridines 3(a-d) were synthesized by the reaction of 2-bromo-4-chlorothieno[3,2-c]pyridine (1) and cyclic amine 2(a-d), which on Suzuki coupling with substituted boronic acids 4(a-f) exclusively converted to corresponding 4-hetero -1-yl-2-arylthieno[3,2-c]pyridine 5(a-x) in good yields. The effect of donor-acceptor substituent on absorption emission properties and fluorescent quantum yield of new thienopyridine derivatives 5(a-x) were studied.

Synthesis of pyrazolopyridine annulated heterocycles and study the effect of substituents on photophysical properties.

Pyrazolo[3,4-b]pyridines having 4-chloro-5-chloroethyl side chain are synthesized by the reaction of 5-aminopyrazole and cyclic ß-formylester gave aminopyrazolodihydrofuranone intermediate, which on cyclization in phosphorous oxychloride exclusively converted in to 4-chloro-5-chloroethyl pyrazolo[3,4-b]pyridines 4(a-b) in major amount. The side chain with acetic acid, thiourea and aromatic amines are used to form angular ring leads to formation of tricyclic Furo[2,3-d]pyrazolo[2,3-b]pyridines 5(a-b), pyrazolo[3,4-b]thieno[2,3-d]pyridines 6(a-b) and pyrazolo[3,4-b]pyrrolo[2,3-d]pyridines 7(a-n) respectively. The substituents effect at C(4) position on fluorescence properties of pyrazolopyridines has been studied. Moreover the effect of electron donor and halogen substituents on fluorescence properties of pyrazolopyrrolopyridines 7(a-n) has been investigated along with their fluorescent quantum yield.

Effect of specific solute-solvent interaction and electron donor-acceptor substituents of novel pyrazolo naphthyridines on fluorescence.

Heterocyclic orthoaminoaldehyde such as 4-amino-3-(4-phenyl)-1-phenyl-1H-Pyrazolo[3,4-b]pyridine-5-carbaldehyde was synthesized by multistep reactions involving reduction of azido derivative 2 with LAH to yield aminoalcohol 3 and oxidation of it with MnO(2) to aminoaldehyde 4.The pyridine ring annulated on to 4 by Friedländer condensation using acetophenones in presence of base to obtained pyrazolo[3,4-h][1,6]naphthyridine 5 in excellent yield. Study of photophysical properties of 5 revealed that the absorption and emission of them depends up on the substituents present on benzene ring in newly annulated pyridine ring.

Synthesis and fluorescence investigation of differently substituted benzo[b][1,8]naphthyridines: interaction with different solvents and bovine serum albumin (BSA).

A series of benzo[b][1, 8]naphthyridines has been synthesized by Friedländer condensation of 2-aminoquinoline-3-carbaldehyde 1 (o-aminoaldehyde) with active methylenes in basic medium. The fluorescence spectroscopic properties of some representative compounds has been studied in different organic solvents; moreover interaction with bovine serum albumin (BSA) in phosphate buffer was examined by UV-vis and fluorescence spectroscopy. The effect of electron donor-acceptor substituents on fluorescence properties of benzo[b][1, 8]naphthyridines 13(a-n) has been investigated along with their fluorescent quantum yields.

Effect of donor-acceptor chromophores on photophysical properties of newly synthesized pyrazolo-pyrrolo-pyrimidines (PPP).

Novel pyrazolo-pyrrolo-pyrimidine (PPP) derivatives having remarkable photophysical properties are designed with the help of theoretical semiempirical calculations. These compounds then synthesized successfully and studied effect of substituents on its photophysical properties.

Arylbenzo[h][1, 6]naphthyridine derivatives: synthesis and photophysical properties.

Suzuki-Miyaura cross coupling was successfully used for C5-arylation in 4-amino-2-chloroquinoline-3-carbaldehyde using arylbornic acid and tetrakistriphenylphosphine palladium catalyst in water. Friedländer condensation reaction on 4-amino-2-chloro/2-arylquinoline-3-carbaldehyde and aromatic ketones gave novel aryl and diarylbenzo[h] [1, 6]naphthyridines in good yields. Fluorescence quantum yields were increased by introducing C2 and C5 π donor aryl benzo[h][1, 6]naphthyridines derivatives.

Synthesis and fluorescence properties of donor-acceptor-substituted novel dipyrazolo[3,4-b:3',4'-d]pyridines (DPP).

A rapid and efficient method for the synthesis of novel dipyrazolo[3,4-b:3',4'-d]pyridines (DPP) from pyrazolo[3,4-b]pyridine was successfully developed. The DPP derivative was further N-alkylated (6, 8) as well as N-linked with amino acids (13) and their photophysical properties were studied along with N-aryl DPP 4 and observed that the chromophores at C(4) position in the aryl ring changed the absorption and emission lambda(max).

Synthesis of novel spiro-oxazino-quinoline derivatives and study of their photophysical properties.

A convenient route was successfully developed for the synthesis of novel heterocycles such as spiro-oxazino-quinoline derivatives from 2-aminoquinoline-3-carbonitrile (4) in good yield. The Spiro-quinoline derivatives (6, 8 and 10) were synthesized and further studied for their photophysical properties. Semiempirical molecular orbital calculation (PM3/PM6 for structure) proves to be a suitable tool for the prediction of absorption and fluorescence properties of these compounds.

Synthesis of quinolone substituted pyrazoles, isoxazoles and pyridines as a potential blue luminophors.

Series of quinolone C(3)-substituted pyrazolines, isoxazolines, pyridines and pyrimidines were synthesized in good yields by the cyclocondensation reactions of 1, 2-unsaturated ketones and hydrazines, hydroxylamine hydrochloride and dimedone respectively. The quinolone derivatives (3, 5 and 7) were synthesized and further studied for their photophysical properties. High absorption and quantum yield are found for N(1)-phenyl and C(3,4)-dimethoxy substituents on phenyl ring (3h). Energy optimization by PM6 methods showed high stability required for selection of suitable candidates to be use as future blue emitters.

Fluorescence properties of donor acceptor chromophores on newly synthesized pyridine-3-carbonitriles.

A convenient route was successfully developed for the synthesis of novel heterocycles such as pyridine-3-carbonitriles 4 from chalcone 3 in good yields. The pyridine-3-carbonitrile derivatives synthesized were further studied for their photophysical properties and observed that absorption and emission was changed, due to the chromospheres at C4-position in phenyl ring and C2-position in pyridine-3-carbonitrile derivatives.

An efficient and safe process for the preparation of ticagrelor, a platelet aggregation inhibitor via resin-NO2 catalyzed formation of triazole ring.

An efficient, safe and improved process for the preparation of ticagrelor 1, a platelet aggregation inhibitor is described. Synthesis comprises the condensation of pyrimidine amine derivative 14 with cyclopentyl derivative 13 in ethylene glycol followed by construction of triazole compound 16 by diazotization of the obtained intermediate 15 with a green and safer reagent "Resin-NO2" in water and acetonitrile mixture. Condensation of 16 with cyclopropylamine derivative 10 followed by deprotection of compound 12 with hydrochloric acid in dichloromethane (DCM) furnished ticagrelor 1 with an overall yield of 65 % and purity of 99.78 % by HPLC. Each reaction stage was optimized independently to establish the scalable and plant friendly process. An efficient and a safe process for key intermediate 14 which involve nitration reaction has also been developed. Safety parameters were established by understanding the thermal events of the reaction by DSC analysis.Graphical abstractSynthesis of ticagrelor via resin-NO2 catalysed formation of triazole ring.

Synthetic tactics of new class of 4-aminothieno[2,3-d]pyrimidine-6-carbonitrile derivatives acting as antimicrobial agents.

Thermal selective reactions were studied on oxothieno[2,3-d]pyrimidine-6-carboxamide 3 with POCl3 and PCl5. At 25-50 °C, the C7-amide rearranges to nitrile furnished compound 4 in 85-90% yield, while at 80-110 °C furnished mixture of products 4 and 5 in 28-68% yields. The chloro displacement with amines in compound 5 yielded 4-aminothieno[2,3-d]pyrimidine-6-carbonitrile derivatives 8(a-h) and 9(a-e). Antimicrobial activity of new compounds was studied against several bacteria such as Staphylococcus aureus MTCC-96, Escherichia coli MTCC-443, Pseudomonas aeruginosa MTCC-4 41, Streptococcus pyogenes MTCC-442 and fungi Aspergillus niger MTCC-282, Aspergillus clavatus MTCC-1323, Candida albicans MTCC-227 using broth microdilution method. Compounds 4, 8b, 8d, 8e, 8h and 9a showed promising antibacterial activity compared to ampicillin and compounds 8b, 8h showed better antifungal activity compared to greseofulvin.

Aminothiophenedicarboxamides and dicyanothiopheneacetamides as effective synthetic molluscicides against Indoplanorbis exustus snail.

New thiophenedicarboxamide 2a-c and dicyanothiopheneacetamide 3a-c derivatives were synthesized and their bioactivity against Indoplanorbis exustus snails was evaluated. The I. exustus snail is a serious host of parasite of genus Schistosoma which infects cattle. Thus reduces livestock productivity and also acts as a source of cercarial dermatitis in human beings. The results obtained show a significant (P < 0.05) molluscicidal activity with LC(50) = 0.6043 ppm for compound 2a and LC(50) = 0.6511 ppm for compound 3a.