Optimizing the white light emission in the solid state isatin and thiazole based molecular hybrids by introduction of variety of substituents on isatin and thiazole ring systems

An efficient and practical 3-component reaction strategy has been developed for the synthesis of a series of multi-colour emissive isatin-thiazole based fluorophores, thiazolylhydrazonoindolin-2-ones (4) from readily available isatins (1), thiosemicarbazide (2) and α-bromoketones (3) in the presence of biodegradable citric acid (0.1 N) in ethanol at reflux temperature for 40-60 min. The reaction proceeds via condensation (C[double bond, length as m-dash]N) and subsequent heterocyclization (C-S & C-N) in one-pot. Nature-friendly reaction profile, easy to perform, wide substrate scope, use of non-hazardous solvents/catalysts, good functional group tolerance, excellent yields (91-98%) in short reaction times, scalability and products do not require column chromatography purification are the attractive features of the present MCR strategy. The photophysical properties of the titled compounds (4) in both solid and solution states have been evaluated. The study reveals that the prepared isatin-thiazole based molecular hybrids exhibited tunable photophysical properties by varying the substituents on both isatin and thiazole motifs. To our delight, the titled compounds, 4k, 4l, 4m, 4u and 4y displayed white light emission with mega Stokes shifts in the solid state.

Emerging green synthetic routes for thiazole and its derivatives: Current perspectives

This review article provides an overview of the green synthesis of thiazole derivatives, emphasizing sustainable and environmentally friendly methodologies. Thiazole derivatives possess significant value and find diverse applications across various fields. However, conventional synthesis methods often involve hazardous reagents and generate substantial waste, posing environmental concerns. The green synthesis of thiazole derivatives employs renewable starting materials, nontoxic catalysts, and mild reaction conditions to minimize environmental impact. Innovative techniques such as microwave irradiation, ultrasound synthesis, green solvents, a green catalyst-based approach, and mechanochemistry-mediated synthesis are employed, offering advantages in terms of scalability, cost-effectiveness, and purification simplicity. The resulting thiazole derivatives exhibit comparable or enhanced biological activities, showcasing the feasibility and practicality of green synthesis in drug discovery. This review paper underscores the importance of sustainable approaches in functional molecular synthesis and encourages further research in this domain.

A Facile and General Oxidative Hydroxylation of Organoboron Compounds: Citric Acid as an Efficient Catalyst in Water to Access Phenolic and Alcoholic Motifs

An efficient and convenient method for the synthesis of phenols and aliphatic alcohols is described in this paper. The oxidative hydroxylation reaction of various organoboron compounds proceeded smoothly by employing H2O2 as the oxidant and citric acid as the catalyst in water at room temperature to produce phenols and aliphatic alcohols in satisfactory to excellent yields (up to 99% yield). Various synthetically useful functional groups, such as halogen atom, cyano, and nitro groups, remain intact during the oxidative hydroxylation. The developed catalytic system also could accommodate phenylboronic pinacol ester and potassium phenyltrifluoroborate to give the target product good yields.

Synthesis, characterization, and anticancer evaluation of novel 4-hydrazinothiazole analogs

Single-step synthesis of novel 4-hydrazinothiazole derivatives 6a-e was achieved under mild conditions using the sequential four-components method involving isothiocyanate, aminoguanidine, carbonyl adduct, and α-haloketone derivatives. Deprotection of these hydrazinothiazoles was influenced by acylation, providing a novel group of diacylated molecular structures with a broader scope for the design of thiazolyl-containing drugs 7a and 7b. FTIR, 1 H/13 C NMR, LC-MS spectroscopy, and CHN elemental analyses were used to study the compound chemical structures. Using a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay on human periodontal ligament fibroblast (HPDLF) cells, the 4-hydrazinothiazole derivatives were screened for cytotoxicity in an in vitro cytotoxicity investigation. The 4-hydrazinothiazole compound 6b bearing an isopropylidene-hydrazino group demonstrated strongly potent cytotoxicity against CAKI1 (IC50  = 1.65 ± 0.24 μM) and A498 (IC50 of 0.85 ± 0.24 μM). Furthermore, the chloroacetyl-containing thiazole compound 7a displayed efficient inhibition of growth against the test cell lines CAKI1 and A498 at low micromolar concentrations, IC50 0.78 and 0.74 μM, respectively.