Panskura Banamali College is located in Panskura, Purba Medinipur district, West Bengal, India. It offers Science, Commerce and Arts degrees in graduation and master's degree in Arts and Science. This institution was established in 1960. The founder of this college was Banamali Charan Khatua for setting up this college. The college is under Vidyasagar University.
Leishmaniasis, a neglected tropical disease, is an epidemic and a public health concern in at least 98 countries. The currently available treatments impose several limitations, including high toxicity, reduced activity, and drug resistance, demanding a quest for novel and effective therapeutics. Since silver and gold-NHC complexes generally display promising biological applications evading drug resistance, in this research work, we have reported the synthesis, structures, structural characterizations, and in vitro antileishmanial activities of a novel series of Ag(I), Au(I), and Au(III) complexes of quinoxaline-wingtip N-heterocyclic carbene (NHC) ligands. The proligands and metal complexes were synthesized and fully characterized by using different spectroscopic techniques and solid-state single-crystal XRD analysis. All the synthesized complexes are investigated for their in vitro antileishmanial potential against intracellular amastigotes of different Leishmania species. Surprisingly, only Au(I) and Au(III)-NHC complexes are effective and display promising antileishmanial activity with IC50 values varying between 0.3 and 17.5 mu M. Structure-activity and toxicity relationships demonstrate the dicationic Au(III)-NHC complex encompassing the phenanthroline ligand as the lead candidate, exhibiting both a high activity and an excellent selectivity index (SI = 157), especially against L. amazonenis. These findings highlight the promising potential of these compounds as alternative therapeutic candidates for the treatment of leishmaniases.
A novel hyperheuristic is designed for solving Generalized Traveling Salesman Problems (GTSP) comprising real and imprecise cost matrices. A novel procedure named K-node rearrangement (KNR) is designed for group sequencing and several strategies are designed for the optimal selection of destinations from distinct groups of the same. The operations are iteratively applied in a nested way for an optimal schedule. 3-opt is applied periodically to enhance the quality of the output. Its efficiency is examined using instances from GTSPLIB having a maximum of 89 groups and 442 destinations, achieving 100
Five defective dicubane Ni2Dy2 complexes with the general formula [Ni2Dy2(L)4X2(solvent)n], where (X = NO3- (1), acetylacetonate (2), NCS- (3), OAc- (4), and pivalate (5)), were synthesized and structurally characterized to investigate how co-ligand variation influences magnetic exchange interactions, anisotropy, and relaxation dynamics. Single-crystal X-ray diffraction reveals that the DyIII ions adopt highly axial coordination environments ranging from distorted square-antiprismatic and triangular dodecahedral geometries in complexes 1-4 to a near pentagonal-bipyramidal geometry in 5. All complexes exhibit zero-field single-molecule magnet behavior, consistent with strong axial ligand fields. CASSCF calculations confirm that the shortest Dy-O(phenoxide) bonds govern the orientation of the magnetic easy axes, aligning toward terminal phenoxide donors. Broken-symmetry DFT calculations indicate uniformly positive Dy-Ni coupling constants, in line with typical ferromagnetic 3d-4f interactions, while the Ni-Ni coupling strength and sign are dictated by the Ni-O-Ni bridging angle, with a crossover between ferro- and antiferromagnetic regimes near 99°. This structural sensitivity rationalizes the comparatively weaker relaxation dynamics observed in complex 3, which features a larger Ni-O-Ni bridging angle accompanied by antiferromagnetic Ni-Ni interactions. These combined experimental and theoretical results establish robust structure-property correlations that provide a rational strategy for tuning anisotropy and exchange topology in Ni-Ln butterfly clusters to advance 3d-4f single-molecule magnet design.
The multidentate hybrid C, N donor N-heterocyclic carbene ligand is used to synthesize an unprecedented Ag(I)-NHC complex and afford controllable assembly of an organometallic Ag(I)-Au(I)-NHC complex. Both experimental and theoretical studies were performed to characterize the organometallic linear chain Ag(I)-NHC polymer (2) and trinuclear grid-like heterobimetallic Ag(I)-Au(I)-NHC cluster (3) starting from 3-picolyl-functionalized multitopic NHC ligand 1-methyl-3-(pyridylmethyl)imidazo[1,5-a]pyridin-4-ylium hexafluorophosphate (1·HPF6). After several spectroscopic studies, including IR, UV-vis, NMR, mass, etc., the final structural characterizations were fully achieved by single-crystal X-ray diffraction, confirming their molecular geometry and coordination environment. Importantly, replacing Ag(I) with sister coinage metal Au(I) led to a distinct transformation from a polymeric linear chain Ag(I) complex, 2, to a well-defined trinuclear Ag(I)-Au(I) mixed metal cluster, 3. Complex 3 leads to a two-dimensional polymer through Au(I)-Au(I) interactions. On the basis of silver and gold chemistry, the optoelectronic properties of 2 and 3 are studied. Current-voltage (I-V) measurements of complexes 2 and 3 reveal Schottky barrier diode (SBD) behavior. Key parameters, including the ideality factor, barrier height, and series resistance, were extracted using thermionic emission (TE) theory. Additionally, space-charge-limited current (SCLC) analysis was employed to determine the charge transport properties, such as the effective carrier mobility and transit time. Notably, Ag(I) complex 2 exhibits higher electrical conductivity compared to that of heterobimetallic Ag(I)-Au(I) complex 3. Our results can be used as a model to understand the optoelectronic properties of other Ag(I) and Au(I) polymeric complexes.
Abstract Three isostructural dinuclear lanthanide complexes, [Ln2(μ-HL)2(HL)2(NO3)2]·4MeCN (Ln = DyIII (1), ErIII (2), YbIII (3)), were synthesized under base-free conditions using the o-vanillin- and 2-aminophenol-based Schiff base H2L. This ligand exhibits two distinct protonation-dependent coordination modes that have not been previously shown in this class of ligands. The simultaneous presence of monoanionic HL and monoanionic zwitterionic HL coordination leads to an unusual combination of chelating and asymmetric bridging features, generating a flexible and moderately axial LnO7N environment. All three complexes display field-induced single-molecule magnet behavior, and complex 1 additionally shows measurable zero-field slow relaxation. Detailed ac susceptibility studies indicate that their relaxation dynamics are dominated by Raman processes, with additional Orbach relaxation in 2 and a direct process in 3. We further combine dc and ac magnetic data with ab initio calculations, providing insight into the relaxation dynamics and the contributions of single-ion anisotropy and weak exchange interactions, if any. The combined structural, magnetic, and theoretical analyses demonstrate that base-free synthesis allows controlled ligand protonation, which in turn modulates crystal field effects and governs the magnetic relaxation pathways in these dinuclear lanthanide systems.
