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Item Active components of tea (Camellia sinensis) extracts and their beneficial application on human health(2024-12-30) Seth, Piya; Mandal, Subhra KantiTea is one of the most frequently consumed beverages across the world and is popular for its classic brew, flavour and wide range of health benefits. The variation in aroma, taste and colour of different kind of teas are caused by the manufacturing process popularly known as fermentation and essentially determine the quality and acceptance of tea flushes. A variety of volatile components such as terpenoids, alcohols, carbonyl compounds, etc. are reported to contribute to the signature tea aromas whereas the non-volatile polyphenolic components (mainly catechins, flavonols, theaflavins, thearubigins), amino acids and xanthines are responsible for the characteristic taste and colour of tea infusions. The nutritional value of tea is mostly gained from the tea polyphenols and amino acids that are reported to possess a broad spectrum of bioactivities, including anti-oxidant properties, reduction of various cancers, inhibition of inflammation and protective effects against diabetes, hyperlipidemia and obesity. Global tea research has generated much in vitro and in vivo data rationally correlating tea polyphenols with their preventive and therapeutic properties against human diseases like cancer, metabolic and cardiovascular diseases etc. Recently, number of studies also suggests that tea polyphenols have the potential to treat or prevent COVID-19 disease. In the current review, we focus on the chemistry behind the signature fragrance, taste and colour of variety of tea and their beneficial account as antioxidant and therapeutic effectiveness against many diseases such as lowering of blood pressure, diabetes, inflammation, anticancer properties and most interestingly against COVID-19 pandemic. Keywords: Tea chemistry, polyphenols, catechins, theaflavins, health benefits, COVID-19.Item Vesicles Formed by Transition Metal Complexes: Synthesis, Morphology and Applications(European Chemistry societies publishing, 2024) Mandal, Subhra Kanti; Seth, PiyaVesicles are one of the most important self-assembled manifes- tations because of their multidimensional applications in biology, catalysis and adsorption. Several synthetic vesicles have been prepared from small peptides, amphiphilic fatty acids, amino acids and organic molecules etc. Transition metal complexes derived from different types of ligands are found to be self assembled to form solid state networks and also supramolecular aggregates in solution. In this review article we have discussed about synthesis, morphology and utility of vesicles formed by 14 transition metal complexes of some amphiphilic and non-amphiphilic ligands. Interestingly, vesicles derived from transition metal complexes with non-amphiphilic ligands are mostly soluble in organic solvents, whereas those derived from amphiphilic ligands are soluble in aqueous medium. As a result, their potential applications can be explored in complementary solvents accordinglyItem An overview of the effect of anionic coligand on structure and magnetic properties of some homometallic NiII and heterometallic NiII-MnII complexes of Schiff base ligands(ELSEVIER, 2024) Mandal, Subhra Kanti; Seth, PiyaHomometallic NiII-Schiff base complexes with various anionic coligands have been widely studied for their structural diversity, catalytic and magnetic properties. Introduction of MnII as heterometal in these complexes is very much challenging to the synthetic and magneto-chemist as MnII possesses higher number of unpaired electrons in high spin ground state. Thus in NiII-MnII heterometallic polynuclear complexes spin–spin interaction and easy axis type magnetic anisotropy can lead to ferromagnetism, antiferromagnetism, ferrimagnetism, etc. In this dissertation we have discussed the synthetic strategies, structural features and magnetic properties of 20 homometallic NiII complexes and 13 heterometallic NiII-MnII complexes derived from some tridentate (N2O), tetradentate (N2O2) and hexadentate (N3O3) Schiff base ligands and various terminally coordinating or bridging anionic coligands (carboxylate, nitrate, nitrite, azide, thiocyanate, dicyanamide etc.). The profound role of anionic coligand in mediating phenoxido bridging angles and hence magnetic behavior of these complexes is also been highlighted.Item A stimuli-responsive L-DOPA-based supramolecular gel for the detection of fluoride ion(Royal society of chemistry, 2024) Mandal, Subhra Kanti; Seth, Piya; Kar, Tanmoy