Solvent-dependent Interactions Research Articles

Unlocking guanine’s potential: Unveiling electronic transitions and nanoelectronic applications through electric field modulation

Guanines, key players in DNA and RNA, exist as dynamic keto and enol forms, influencing reactivity and potential applications. This study explores the impact of external electric fields on these forms using computational methods in gas and solvent (water) phases. Analyzing the energy gap, dipole moment, enthalpy, and Gibbs free energy revealed distinct responses. The keto form showed a significant decrease in the energy gap in the presence of an electric field, particularly in water, indicating enhanced reactivity. Conversely, the enol form exhibited a stabilizing effect with increasing electric field strength. Thermodynamic properties highlighted solvent-dependent interactions and electric field-induced changes in electron density distribution. The study further investigated guanine’s potential for nanoelectronics by calculating I-V curves, revealing promising characteristics, especially for the keto form in the aqueous phase. Additionally, the analysis of solvation and cohesive energies provided insights into solute–solvent interactions and intrinsic molecular stability. Overall, this research contributes to understanding how guanine responds to electric fields, paving the way for novel guanine-based materials with potential applications in nanoelectronics.

Solvation effect on photophysical properties and ESIPT behaviours for 2-benzooxazol-2-yl-6-thiophen-2-yl-phenol fluorophore: a theoretical study

Inspired by its potential applications of organic luminescence and fluorescence probe materials for 2-(2′-hydroxyphenyl)benzazoles (HBX) derivatives, this study mainly investigates the excited-state behaviours of a novel 2-benzooxazol-2-yl-6-thiophen-2-yl-phenol (BYTYP) fluorophore. Theoretical exploration has been conducted on the solvent-dependent interactions of excited-state intramolecular hydrogen bonding and the process of excited-state intramolecular proton transfer (ESIPT) for BYTYP. By combining optimised geometrical modifications, infrared (IR) vibrational spectra and the core-valence bifurcation (CVB) index, hydrogen bonding strengthening can be confirmed. Predicting the bond energy (E HB), we assert that nonpolar solvents are more conducive to enhancing hydrogen bonding interactions. The ESIPT tendency of BYTYP is further elucidated by charge reorganisation resulting from photoexcitation. By exploring potential energy surfaces (PESs) and identifying transition states (TS), we have uncovered the solvent-polarity-controlled ESIPT behaviours. We hope these insights into excited-state dynamics will facilitate the design and development of novel fluorescent sensors in future.

Solvent-Controlled Excited State Relaxation Path of 4-Acetyl-4'-(dimethylamino)biphenyl.

Stationary and picosecond time-resolved fluorescence (TRF) and absorption spectra were compared in different aprotic solvents at various temperatures for 4-acetyl-4'-(dimethylamino)biphenyl (ADAB). A large value of the excited state dipole moment, 18-25 D, was estimated from the plot of solvatochromic shift. TRF spectra of ADAB recorded as a function of solvent polarity and temperature show unusual temporal evolution (shift and decay) of the fluorescence bands. In some cases, the dynamic Stokes shifts occur on a time scale much shorter than expected on the basis of literature data on solvent relaxation. In order to investigate variations in the energy of electronic transitions, oscillator strengths, and dipole moments upon changing the molecular geometry, quantum chemical modeling (DFT, TD-DFT, CIS) was performed for ADAB and its ground-state pretwisted derivative, 4-acetyl-4'-dimethylamino-2,2'-dimethylbiphenyl (ADAB-Me). Combination of spectroscopic data and computational results leads to the model of excited state relaxation which involves dynamic solvent-dependent interaction between two close-lying (1)nπ* and (1)ππ* excited electronic states.

Solvent dependent interactions between droplets in water-in-oil microemulsions.

In this paper, we investigated the dilution enthalpies of the droplets in water/AOT/oil microemulsions with oil being isooctane, decane, or cyclohexane by isothermal titration microcalorimetry (ITC). Combining with the results obtained from the study of the water/AOT/toluene system in our previous work, it was found that the enthalpy interactions between droplets for isooctane and decane systems were repulsive, while the enthalpy interactions were attractive for cyclohexane and toluene systems. The repulsive droplet interaction for the isooctane system was also confirmed by static light scattering. The solvents appear to play important roles in varying the droplet enthalpy interactions from positive to negative, and the entropy contribution seems to be dominant for the stability of these microemulsion droplet systems.

Amphiphilic polymer conetworks as chiral separation membranes

There is an urgent need for enantiopure chemicals, e.g., as basic compounds for pharmaceuticals. Although great progress has been made to obtain these compound using chiral catalysts, enzymes or even whole cells, it is often not possible or at least not economic to obtain enantiopure compounds. Thus enantioseparation is still required. Besides the elaborate and expensive chromatography and crystallization techniques, chiral membranes have been found to be effective in enantioseparation. Generally such membranes have to be developed specifically for a certain compound in a suited solvent. This is an elaborate development, because little is known about the complex transport process through a chiral membrane. In order to get better insights in the function of such membranes, we have designed a new class of chiral separating membranes that are applicable for nearly every solvent and therefore potentially many substrates. The conetworks are based on nanophasic, amphiphilic polymer conetworks (APCN) featuring a chiral phase of poly(( R),( S)- N-(1-hydroxy-butan-2-yl)acrylamide) (P-( R),( S)-HBA) and a non-chiral polydimethylsiloxane (PDMS) phase. This APCN allows to directly exploring interactions between a chiral membrane and an enantiopure compound in dependence on a broad range of solvents varying from n-heptane to water by simply measuring the permeabilities of the compounds. Besides the numerous insights in the solvent-dependent interactions between membrane and five model substrates, we demonstrate that the APCNs are excellent chiral separation membranes. Further, it could be shown that the superior selectivity of these materials is based on the structure of their nanophases.

Double C-H activation in a Rh-NHC complex leading to the isolation of a 14-electron Rh(III) complex.

The solvent-dependent interaction of ItBu with a Rh(I)-olefin complex leads to the isolation of two precursors en route to a unique double cyclometalation process. Abstraction of the chloride ligand from the resulting complex enables the isolation of a "bare" 14-electron Rh(III) complex.

Bioadhesion - a phenomenon with multiple dimensions

This paper reviews some relevant citations regarding the non-specific forces that must be considered in oral bioadhesive events. These range from forces related to restorative dentistry to those related to prevention and molecular biology. Types of interactions discussed are: 1. Van der Waal's forces; 2. electrostatic double-layer forces; 3. solvent-dependent interactions; 4. hydrogen bonding; 5. hydrophobic interactions; 6. hydration forces; 7. steric forces; and 8. covalent bonds. Examples are given of the various types of interaction that occur at different surface separation (< or =400 A) between adsorbed films of a pure salivary protein fraction (PRP1).