Adsorption of a thione bioactive derivative over different silver/gold clusters – DFT investigations

Examining the adsorption and sensing characteristics of cytosine (CTE) on Y9N9 (Y = Al, B, Ga) nanorings using solvent effects, DFT, AIM and SERS analyses

Nucleobases are nitrogenous biological compounds that are more significant in a range of biological and in medical applications. They are constituents of nucleotides in deoxyribonucleic acid (DNA) and ribonucleic acid (RNA). Therefore, we assessed the sensing applicability by studying the cytosine (CTE)-Y9N9 (Y = Al, B, Ga) nanoring interaction using density functional theory. It was evident that CTE interacted strongly with each ring. Due to charge transfer between the nanoring and CTE, a dipole moment (DM) is generated. All complexes have band gaps less than that of CTE. Complexes' band gap energies are lower in aqueous phase and vacuum than they are in pristine rings. All complexes exhibit higher adsorption energies in solvent medium in comparison with that in vacuum. Changes in the frontier molecular orbitals (FMOs) energies of nanorings after interaction have a major impact on their electrical conductivity and work function. In addition to being an electrical sensor, the Y9N9 nanorings for CTE can also be utilized as a work function-based sensor. But Y9N9's CTE recovery time indicates that it can be used to extract or store CTE depending on the environment. The current work can be expanded to examine the impact of Ag/Au/Cu doping using Y9N9 in order to examine the characteristics of drug delivery carriers and the consequence of doping. The interaction between the analyte and substrate was further studied using reduced density gradient (RDG) analysis, comparing the nature and strength of the interaction in both vacuum and aqueous medium. The observations revealed a stronger interaction in the presence of an aqueous medium, which aligns with the higher adsorption energy values.

SERS analysis, DFT, and solution effects regarding the structural and optical characteristics of folic acid biomolecule adsorbed on a Cu3 metal cluster

The optical characteristics of folic acid (ABP) and metal clusters of copper (Cu3) at various locations were investigated by means of density functional theory (DFT) computations. Mulliken charge analysis and molecular electrostatic potential (MEP) surface show how charge moves from Cu3 to ABP through the various groups. The peak in the UV-Vis spectra of ABP-Cu3 is caused by bonding and anti-bonding orbitals. In both vacuum and aqueous conditions, the polarizability values of ABP-Cu3 cluster are significantly higher than those of pure ABP, indicating a possible enhancement of the nonlinear optical (NLO) effect. Our research investigates the possibility of using ABP adsorbed metal clusters for NLO materials. Surface enhanced Raman scattering (SERS) in the ABP adsorbed metal clusters enhances the vibrational modes of ABP. Adsorption energies are found to be in the range -17.08 to -58.52 kcal/mol in vacuum and -53.34 to -93.44 kcal/mol in aqueous medium for the different configurations for ABP-Cu3. It indicates that metal clusters adsorbed by ABP are stable in the aqueous media. Experimental IR and UV-Vis of ABP is in agreement with theoretically predicted ones.

Comprehensive Study of the Chemistry behind the Stability of Carboxylic SWCNT Dispersions in the Development of a Transparent Electrode

Single-walled carbon nanotubes (SWCNTs) are well-known for their excellent electrical conductivity. One promising application for SWCNT-based thin films is as transparent electrodes for uncooled mid-IR detectors (MIR). In this paper, a combination of computational and experimental studies were performed to understand the chemistry behind the stability of carboxylic SWCNTs (SWCNTs-COOH) dispersions in different solvents. A computational study based on the density functional tight-binding (DFTB) method was applied to understand the interactions of COOH-functionalized carbon nanotubes with selected solvents. Attention was focused on understanding how the protonation of COOH groups influences the binding energies between SWCNTs and different solvents. Thin film electrodes were prepared by alternately depositing PEI and SWCNT-COOH on soda lime glass substrates. To prepare a stable SWCNT dispersion, different solvents were tested, such as deionized (DI) water, ethanol and acetone. The SWCNT-COOH dispersion stability was tested in different solvents. Samples were prepared to study the relationship between the number of depositions, transparency in the MIR range (2.5–5 µm) and conductivity, looking for the optimal thickness that would satisfy the application. The MIR transparency of the electrode was reduced by 20% for the thickest SWCNT layers, whereas sheet resistance values were reduced to 150–200 kΩ/sq.

DFT analysis of valproic acid adsorption onto Al12/B12-N12/P12 nanocages with solvent effects

Using density functional theory, the adsorption of valproic acid onto the surface of fullerene-like nanocages was investigated. Valproic acid interacts with the nanocages through the carboxylic group with energies of - 144.14, - 109.71, - 105.22, and - 84.96 kcal/mol. The frontier molecular orbital (FMO) energy levels were considerably altered upon adsorption, resulting in a reduction in energy gap and increase in electrical conductivity. This suggests that nanocages could be used as sensors as well as options for drug administration in biological systems. Solvation effects in water are also reported.