Importance Of Solvents Research Articles

Unraveling the Solvent Regulation in the Heteroatom-Doped Endohedral Gold Clusters: A Theoretical Study on the Electronic Properties and O2 Activation.

Liquid-phase synthesis of atomically precise nanoclusters has experienced rapid development recently, where polar solvents are indispensable in such a process. However, the regulation effect of solvents on the structural and electronic properties of different metal clusters and cluster assembly materials is still not well understood. Herein, a comprehensive density functional theory calculation has been performed to explore the solvation effect on heteroatom-doped endohedral gold clusters that always have remarkable stabilities and tunable electronic structures. The solvation free energy of the M@Au12 clusters (M = Cr, Mo, W, Co, Rh, Ir, Cu, Ag, and Au) was found to be related to the charge distribution of the central doped-atom M and the outer Au12 cage. Moreover, the aqueous solvent was observed to be able to increase the adsorption capacity of M@Au12 to O2 following the activation of O2 through the charge transfer from M@Au12 to O2, in which the transferred electrons occupy the π antibonding orbital of O2. In addition, the water solvent can also improve the hydrogenation reaction of O2 to form OOH over M@Au12, where the activation energy barrier for this process is very low with the participation of the solvent. Considering the importance of solvents in the liquid-phase synthesis of atomically precise clusters, these findings highlighted here could provide valuable theoretical guidance in potential applications of functional gold nanoclusters, especially in the liquid-phase cluster catalysis.

Natural pigments: Origin and applications in dye sensitized solar cells

Abstract Dye Sensitized Solar cells (DSSCs) have emerged as green energy solution due to their low cost and easy processability. Four key components (working electrode, sensitizer, redox mediator and counter electrode) of these third generation solar cells makes its fabrication less complex and simple. However, some limitations associated with these astonished devices needed to be fixed that gave birth to the development and application of many new materials viz. graphene, nanomaterials, quantum dots, metal sulphides, natural sensitizers in DSSCs. This article provides a brief overview of DSSCs employing natural pigments as sensitizers, different types of materials as an electrode, and applications of graphene in natural DSSCs. The importance of solvents and dipping time has also discussed to improve the efficiency of DSSCs.

Importance of Solvents' Translational-Rotational Coupling for Translational Jump of a Small Hydrophobic Solute in Supercooled Water.

Despite clear evidence of sudden translational jump occurrence of a solute in supercooled water, a detailed mechanism of this jump is still lacking. A previous work [ Indra , S. ; Daschakraborty , S. Chem. Phys. Lett. 2017 , 685 , 322 - 327 ] put forward a mechanism of this jump from an initial solvent cage to a final one. The proposed mechanism is astoundingly similar to that of the electron/proton transfer reaction in aqueous solution. The above study identified the spatial prearrangement (rearrangement before the jump occurrence) of cage forming water solvent molecules as the actual reaction coordinate. However, the study completely ignored the contribution of the orientational prearrangement of solvent water molecules. In this study, we have monitored both the spatial and the orientational prearrangements of water solvent molecules at subzero temperatures during the jump occurrence of the solute. We have found overwhelming contributions of both the spatial and orientational prearrangements of water, which symmetrize the hydration structure at the initial and final cage positions to facilitate the jump event. Through a systematic temperature dependence study (from T = 240 to 270 K), we have found clear evidence that a strong synchronization between translational and rotational prearrangements of the solvent water molecules is crucial for the solute's jump from one solvent cage to another in supercooled water (below T = 252 K). The above translation-rotation synchronization is probably due to the cooperative movement of solvent water molecules forming clusters in the supercooled region. Since these cooperative dynamics are the consequence of the spatiotemporal heterogeneity in the medium, we infer that the large-amplitude translational jump of the nonpolar solute probably stems from the spatiotemporal heterogeneity of supercooled water. At temperatures above the melting point, this cooperativity is partly lost since the translational and orientational prearrangements become somewhat independent of each other.

Importance of solvents in preparing highly active Ti-SBA-15 catalysts by grafting method

The importance of solvents in preparing Ti-incorporated SBA-15 mesoporous silica (Ti-SBA-15) of highly catalytic activities in epoxidation of bulky alkenes using titanium alkoxides as grafting agents was disclosed. Solvents were found to markedly affect the coordination environment of Ti incorporated on SBA-15. Among the common solvents examined, best dispersion of tetrahedrally coordinated Ti(IV) on silica surface was obtained by grafting in 1-butanol and the second was in 1-hexanol. It is attributed to that the hydrolysis of titanium alkoxides in these alcohols is slower than in other studied solvents, including short-chain alcohols and non-polar hydrocarbons. Detailed studies on the hydrolysis rates of titanium alkoxide in different solvents were examined. In contrast, titanium alkoxides of different alkyl groups as titanium sources were found to have little influences on the structures and catalytic activities of resultant Ti-SBA-15 materials. Ti-SBA-15 of high Ti loading (ca. 4.2% Ti/Si ratio) prepared by grafting with TBOT in 1-butanol was found to have optimal catalytic activities in epoxidation of cycloalkenes, including cyclohexene and dicyclopentadiene, using tert-butylhydroperoxide as the oxidant.

Impact of synthetic routes on the structural and physical properties of butyl-1,4-diammonium lead iodide semiconductors

We report the significant role of synthetic routes and the importance of solvents in the synthesis of organic–inorganic lead iodide materials.

Metal-assisted reactions. Part 24. The importance of solvents in liquid-phase heterogeneous catalytic transfer reduction

In liquid-phase catalytic transfer reduction in which a hydrogen donor is used to effect hydrogenation of a substrate, reaction often proceeds sluggishly in single phase solvents but goes rapidly in biphasic solvent systems in which the catalyst usually resides in one or other of the phases. Depending on the nature of the substrate and donor, an excess of either can lead to the catalyst surface becoming saturated with one component, thereby preventing reaction. It is shown that the biphasic solvent system is, in practice, a simple means of controlling access to the catalyst by either the substrate or donor such that both are present on the surface in comparable amounts, leading to optimum or near optimum reaction rates.

Investigation of effect of solvent quality on Indonesian subbituminous coal liquefaction under short contact time conditions

The role of the solvent upon Indonesian subbituminous coal during short contact time liquefaction in microreactors is examined by using various solvents such as non-polar hydroaromatics, non-polar aromatics, polar hydroaromatics and polar aromatics. The importance of solvents on the ability to convert coal to pyridine soluble (coal conversion) and pentane soluble (oil yield) products is evaluated. The hydrogen donor capability of the solvent is found to be the most important controlling factor. In the absence of hydroaromatics, such phenolic compounds as 1-naphthol can improve coal conversion, but a highly negative yield of oil is observed.