Publications by authors named "Amit Pratap Singh"

Acne vulgaris is a common dermatological disorder, with current treatments often limited to poor skin penetration, instability, irritation and suboptimal therapeutic outcomes. There is a pressing need for advanced drug delivery systems that can overcome these limitations and enhance treatment efficacy. This study aimed to develop and optimise a novel tazarotene-loaded emulgel formulation, combining the advantages of emulsions and gels to achieve controlled drug release, improved stability and superior clinical performance in topical acne therapy.

View Article and Find Full Text PDF

Background: Although humic substances are the principal ingredients in processed humic products, there has been no practical way to determine if a material is humified, allowing fake products to be used by farmers instead of genuine humic substances.

Objective: To develop a test method using conventional laboratory techniques to determine if a material is humified.

Method: A neutralized extract is prepared using the standardized extraction protocols specified in ISO 19822:2018(E).

View Article and Find Full Text PDF

A BODIPY (4,4-difluoro-4-bora-3a,4a-diaza-s-indacene) based pioneering sensing material (HL) having 2-amino pyridine as receptor was synthesized and used for the selective detection of Hg ions. The synthesized HL features a high affinity towards Hg (k = 2.04 × 10 M), accompanied by effective quenching of fluorescence in DMF:HO (1:9 v/v, 10 mM HEPES buffer, pH 7.

View Article and Find Full Text PDF

Two novel malonyl-based chemosensors, N,N'-bis(ethyl-4'-benzoate)-1,3-propanediamide (1) and N,N'-bis(ethyl-3'-benzoate)-1,3-propanediamide (2), have been synthesized and screened towards various biologically important metal ions such as Na, Mg, K, Ca, Al, Cr, Mn, Fe, Fe, Co, Ni, Cu, Zn, Ag, Cd, Hg, Ti, and Pb. The emission spectral studies of both 1 and 2 displayed 84 - 91% turn-off emission responses selectively with Fe ion in aqueous buffer (MeCN/HO, 1:4, v/v, pH = 7.4) solution.

View Article and Find Full Text PDF

The benefits of the ultrafast magic-angle spinning (MAS) approach for the acquisition of ultrawide-line NMR spectra-spectral simplification, increased mass sensitivity allowing the fast study of small amounts of material, efficient excitation, and application to multiple heavy nuclei-are demonstrated for tin(II) oxide (SnO) and the tin complex [(LB)Sn(II) Cl](+) [Sn(II) Cl3 ](-) [LB=2,6-diacetylpyridinebis(2,6-diisopropylanil)] containing two distinct tin environments. The ultrafast MAS experiments provide optimal conditions for the extraction of the chemical-shift anisotropy tensor parameters, anisotropy, and asymmetry for heavy spin-1/2 nuclei.

View Article and Find Full Text PDF

Single-crystal X-ray diffraction (XRD) is often considered the gold standard in analytical chemistry, as it allows element identification as well as determination of atom connectivity and the solid-state structure of completely unknown samples. Element assignment is based on the number of electrons of an atom, so that a distinction of neighboring heavier elements in the periodic table by XRD is often difficult. A computationally efficient procedure for aspherical-atom least-squares refinement of conventional diffraction data of organometallic compounds is proposed.

View Article and Find Full Text PDF

Oxidation reactions of stable chalcogenamides with iodine are intriguing due to their broad application in various organic syntheses. In the present study we report on the utilization of N-heterocyclic carbene and cyclic-alkyl-amino carbenes L(1-3): (L(1): = :C[N(2,6-iPr2-C6H3)CH]2, L(2): = :C(CH2)(CMe2)(C6H10)N-2,6-iPr2-C6H3, L(3): = :C(CH2)(CMe2)2N-2,6-iPr2-C6H3) for the syntheses of chalcogenamides L(1-3)=E (E = S, Se, Te) 1-4 and zwitterionic adducts L(1-3)=E-I-I 5-8. The synthesis of compounds 1-4 involved the addition reaction of ligand L(1-3): and elemental chalcogen.

View Article and Find Full Text PDF

Metal ions with radical centers in their coordination sphere are key participants in biological and catalytic processes. In the present study, we describe the synthesis of the cAAC:ZnCl2 adduct (1) using a cyclic alkylaminocarbene (cAAC) as donor ligand. Compound 1 was treated with 2 equiv of KC8 and LiB(sec-Bu)3H to yield a deep blue-colored dicarbene zinc compound (cAAC)2Zn (2) and the colorless hydrogenated zinc compound (cAACH)2Zn (3), respectively.

View Article and Find Full Text PDF

Two different synthetic methodologies of silicon dihalide bridged biradicals of the general formula (L(n)•)2SiX2 (n = 1, 2) have been developed. First, the metathesis reaction between NHC:SiX2 and L(n): (L(n): = cyclic akyl(amino) carbene in a 1:3 molar ratio leads to the products 2 (n = 1, X = Cl), 4 (n = 2, X = Cl), 6 (n = 1, X = Br), and 7 (n = 2, X = Br). These reactions also produce coupled NHCs (3, 5) under C-C bond formation.

View Article and Find Full Text PDF

Dialkylamino compounds of group 14 elements (Si, Ge, Sn) in the +2 oxidation state supported by benzamidinate ligands were synthesized and treated with pentafluoropyridine. Two different modes of reactivity were observed, depending on the metal atom and the basicity of the substituent at the metal. Pentafluoropyridine undergoes oxidative addition reaction at the Si(II) and Ge(II) atoms whereas at the Sn(II) atom substitution of the NMe(2) group by the para fluorine of pentafluoropyridine occurs.

View Article and Find Full Text PDF

An abnormal N-heterocyclic carbene (aNHC) has been used as a Lewis base to initiate dismutation of trichlorosilane. This report presents the reactivity differences of a normal N-heterocyclic carbene (NHC) versus aNHC with heavier group 14 elements. Three novel compounds (NHC)(2)·SiCl(2)H(2) (2), aNHC·SiCl(2)H(2) (3), and aNHC·GeCl(2) (4) have been synthesized and characterized by single crystal X-ray analysis, solid-state NMR and DFT calculations.

View Article and Find Full Text PDF

Cationic and anionic species of heavier low-valent group 14 elements are intriguing targets in main group chemistry due to their synthetic potential and industrial applications. In the present study, we describe the synthesis of cationic (MCl(+)) and anionic (MCl(3)(-)) species of heavier low-valent group 14 elements of germanium(II) and tin(II) by using the substituted Schiff base 2,6-diacetylpyridinebis(2,6-diisopropylanil) as Lewis base (LB). Treatment of LB with 2 equiv of GeCl(2)·dioxane and SnCl(2) in toluene gives compounds [(LB)Ge(II)Cl](+)[Ge(II)Cl(3)](-) (1) and [(LB)Sn(II)Cl](+)[Sn(II)Cl(3)](-) (2), respectively, which possess each a low-valent cation and an anion.

View Article and Find Full Text PDF

We report the synthesis and structural characterization of two-dimensional {Co(3+)-Zn(2+)} and {Co(3+)-Cd(2+)} heterobimetallic networks and their catalytic applications in heterogeneous and solvent-free ring opening reactions of various epoxides.

View Article and Find Full Text PDF

Two {Co(3+)-Zn(2+)} heterobimetallic coordination networks have been synthesized utilizing Co(3+) complex as the building blocks. The structural studies reveal 2D sheet-like networks where the Co(3+) containing building blocks are connected through Zn(2+) ions. Two different building blocks generate two unique networks as evidenced by the crystallographic studies and other properties.

View Article and Find Full Text PDF