Gopal K. Mehrotra

Ionic Liquid: Best Alternate to Organic Solvent to Carry Out Organic Synthesis

ABSTRACT Ionic liquids, being composed entirely of ions, that is, cations and anions, were once mainly of interest to electrochemists and organic chemists. Ionic liquid has prodigious potential as an environmentally benign reaction medium for sustainable chemical synthesis. Since the end of the 1990s, rapidly increasing research efforts have shown that ionic liquid can replace conventional and potentially hazardous organic solvents in a wide range of organic synthesis due to their versatile applications. There is also increasing evidence that the application of ionic liquid can broaden the scope of catalytic behavior. Recently, however, it has become apparent that, inter-alia, their lack of measurable or low vapor pressure proved them as green solvents for the organic synthesis and that a wide range of chemical reactions can be performed in them as discussed in this review.

Cation-templated 2-D Mn(II)–oxalate framework with an acyclic tetrameric water cluster

The single-crystal X-ray structure of a cation-templated manganese–oxalate coordination polymer [NH(C2H5)3][Mn2(ox)3] · (5H2O)] (1) is reported. In 1, triethylammonium cation is entrapped between the cavities of 2-D honeycomb layers constructed by oxalate and water. The acyclic tetrameric water clusters and discrete water assemble the parallel 2-D honeycomb oxalate layers via an intricate array of hydrogen bonds into an overall 3-D network. The magnetic susceptibility, with and without the water cluster, are reported with infrared and EPR studies.

Theoretical model to investigate the alkyl chain and anion dependent interactions of gemini surfactant with bovine serum albumin

Surfactants are used to prevent the irreversible aggregation of partially refolded proteins and they also assist in protein refolding. We have reported the design and screening of gemini surfactant to stabilize bovine serum albumin (BSA) with the help of computational tool (iGEMDOCK). A series of gemini surfactant has been designed based on bis-N-alkyl nicotinate dianion via varying the alkyl group and anion. On changing the alkyl group and anion of the surfactant, the value of Log P changes means polarity of surfactant can be tuned. Further, the virtual screening of the gemini surfactant has been carried out based on generic evolutionary method. Herein, thermodynamic data was studied to determine the potential of gemini surfactant as BSA stabilizer. Computational tools help to find out the efficient gemini surfactant to stabilize the BSA rather than to use the surfactant randomly and directionless for the stabilization. It can be confirmed through the experimental techniques. Previously, researcher synthesized one of the designed and used gemini surfactant to stabilize the BSA and their interactions were confirmed through various techniques and computational docking. But herein, the authors find the most competent gemini surfactant to stabilize BSA using computational tools on the basis of energy score. Different from the single chain surfactant, the gemini surfactants exhibit much stronger electrostatic and hydrophobic interactions with the protein and are thus effective at much lower concentrations. Based on the present study, it is expected that gemini surfactants may prove useful in the protein stabilization operations and may thus be effectively employed to circumvent the problem of misfolding and aggregation.

Zn-nicotinate complex – a precursor for ZnO nanoparticles

A zinc-nicotinate complex has been prepared by direct reaction of zinc acetate and nicotinic acid in the presence of template tetramethylethylenediamine and is characterized by elemental analysis, FTIR, and TGA/DTA. The Zn complex was a precursor for the synthesis of ZnO nanoparticles. A correlation of the thermal and spectral properties of the precursor complex with its structure has been discussed. Thermolysis under air was studied by thermogravimetry, and the resulting ZnO product was characterized by XRD and TEM, showing compact particles with a diameter of about 17–50 nm.

Efficient one-pot four-component synthesis of fused thiazolopyridin-2-ones in ionic liquid

AbstractAn efficient one-pot synthesis of fused thiazolopyridinone derivatives (5-amino-6,7-diphenyl-4,7-dihydro-3H-thiazolo[4,5-b]pyridin-2-ones) by four-component reaction of aldehyde, benzylcyanide, ammonium acetate and thiazolidine-2,4-dione in ionic liquid is reported. This protocol has the advantages of environmental friendliness, higher yields, less reaction time, and convenient operation. Also, optimization of the synthesized compounds has been done using Hyperchem 8.0. Graphical AbstractAn efficient one-pot synthesis of fused thiazolopyridinone derivatives (5- amino-6,7-diphenyl-4,7-dihydro-3H-thiazolo[4,5-b]pyridin-2-ones) by fourcomponent reaction of aldehyde, benzylcyanide, ammonium acetate and thiazolidine-2,4-dione in ionic liquid is reported. This protocol has the advantages of environmental friendliness, higher yields, less reaction time, and convenient operation.

Gelatin Nanocomposites (GNCs): An Efficient Drug Delivery System

The literature reported that natural proteins are being widely used as potential carriers for site-specific drug delivery as they bear nontoxic and biocompatible behavior. Modified proteins have shown also their potent role in gene delivery, cell culture, and tissue engineering. Gelatin is one of the most versatile widely used proteins in pharmaceutics because of biocompatibility, biodegradability, low cost, and other applications. These advantages led to its application in the synthesis of nanoparticles to deliver drugs and genes in the last few decades. Impact of gelatin binding to various drugs has been investigated for controlled release applications by various research groups. Various parameters like cross-linking density and isoelectric point can be used to tune the optimization of gelatin degradation and drug delivery kinetics. At present, gelatin nanocomposites play a crucial role in various aspects of biology and medical sciences. Various cross-linkers used to improve the physicochemical behavior of gelatin nanocomposites (GNCs) have been reported. Further, physicochemical behaviors of GNCs including drug loading, release, particle size, zeta-potential, cytotoxicity, cellular uptake, and stability are explained. Various groups explained the applications of GNCs in delivery of drugs and genes as well as their in vivo pharmacological performances. Our emphasis is to study the interaction of various factors of biological macromolecules in the extracellular matrix which regulate the function of bioactive molecules. In light of the importance of GNCs, gelatin has proven to be a good biomaterial for the controlled release of several biologically active molecules. Although, research is still continued to improve the role of gelatin to release drugs/genes through the use of composite scaffolds and gelatin modification.

Metal NPs (Au, Ag, and Cu): Synthesis, Stabilization, and Their Role in Green Chemistry and Drug Delivery

Nature is very powerful and strategic and has tailored various materials with sizes in nanometers. This phenomenon is observed with the passage of time. In the current picture, the most important thing is to control the changes in biological processes at the nanoscale. Due to this behavior of nature, scientists and academicians have been inspired and encouraged towards nanoscience and nanotechnology and reproducing the manufacture and controlled synthesis of nanomaterials in bulk. Nanoscience is the interdisciplinary science where basics and the advancement of the discipline of the fundamental principles of atoms and molecules have been discussed regarding their structures in various dimensions where the particle size is less than 100 nm. Nanoparticles are popular due to their high specific surface area and good dispersion in various solvents. Therefore, metal nanoparticles (NPs) have been applied in different areas of science including medicine, electronics, electrical, and catalysis, among others. The synthesis of metal NPs in bulk is a challenge to researchers due to their aggregation behavior. Thus, the stabilization of metal nanoparticles becomes a challenging job. But in the last decade ionic liquids (ILs) were found to be potent alternatives for the stabilization of metal nanoparticles.

Role of Ionic liquid in Stabilization/ destabilization of metal NPs

AbstractInteraction of metal NPs with different number of ILs was studied. Basically, different energies for the interaction of various metal NP with the different number of tetrazole based ionic liquid were calculated. Herein, energies in terms of moldoc and rerank score have been calculated. How metal NPs interacts with ionic liquid in different ratio? Ionic liquid interaction energy increases on increasing the number of ionic liquids both in case of moldoc score and rerank score. Only exception has been seen when two molecules of ionic liquids interact with metal NPs showed the maximum stability. As far as metal NPs-IL interaction energy is concerned it again follows the same trend, it increases but again decreases in case of two ionic liquids. Steric interaction energy is also following the same trend. This energy is pairwise energy. Further, the deciding factor for the stability is the total energy and it increases with increase in number of IL and therefore, when the interaction of metal NPs was car...

Diaquabis(nicotinamide-κN1)bis(thiocyanato-κN)nickel(II)

In the title complex, [Ni(NCS)2(C6H6N2O)2(H2O)2], the NiII ion is located on an inversion center and is coordinated in a distorted octahedral environment by two N atoms from two nicotinamide ligands and two water molecules in the equatorial plane, and two N atoms from two thiocyanate anions in the axial positions, all acting as monodentate ligands. In the crystal, weak N—H⋯S hydrogen bonds between the amino groups and the thiocyanate anions form an R 4 2(8) motif. The complex molecules are linked by O—H⋯O, O—H⋯S, and N—H⋯S hydrogen bonds into a three-dimensional supramolecular structure. Weak π–π interactions between the pyridine rings is also found [centroid–centroid distance = 3.8578 (14) Å].

Di-aqua-bis-(nicotinamide-κN (1))bis-(thio-cyanato-κN)nickel(II).

In the title complex, [Ni(NCS)2(C6H6N2O)2(H2O)2], the NiII ion is located on an inversion center and is coordinated in a distorted octahedral environment by two N atoms from two nicotinamide ligands and two water molecules in the equatorial plane, and two N atoms from two thiocyanate anions in the axial positions, all acting as monodentate ligands. In the crystal, weak N—H⋯S hydrogen bonds between the amino groups and the thiocyanate anions form an R 4 2(8) motif. The complex molecules are linked by O—H⋯O, O—H⋯S, and N—H⋯S hydrogen bonds into a three-dimensional supramolecular structure. Weak π–π interactions between the pyridine rings is also found [centroid–centroid distance = 3.8578 (14) Å].