Structural Chemistry最新文献

Piperidine derivatives are versatile scaffolds with significant potential in drug design due to their broad range of biological activities. In this study, density functional theory (DFT) and molecular dynamics (MD) simulations were employed to investigate the structural, electronic and biological properties of select piperidine-based compounds (1–8). DFT calculations of all the piperidine analogues (1–8) provided insights into molecular geometry, electronic stability and reactivity, MD simulations (100 ns) in explicit solvent revealed key conformational behaviors and interactions including root-mean-square deviation (RMSD), hydrogen bonding, and solvent-accessible surface area elucidating their molecular interactions in a biological environment. Compounds 2 and 4 were evaluated for their inhibitory potential against α-glucosidase and cholinesterase enzymes providing insight into their inhibitory potential and molecular binding interactions with these targets. This study uniquely correlates the structural stability and flexibility of piperidine derivatives with specific functional groups, offering valuable insights for drug design and supporting further experimental and computational exploration.

Benzothiazole-based fluorescent probes, exhibiting promising optical properties, have been widely developed for the detection of chemical and biological contaminants. Density functional theory (DFT) and time-dependent density functional theory (TD-DFT) methods were employed to investigate the sensing mechanism of NO detection using the ratio fluorescence probe 2-(2,3′,5-trimethyl-[1,1′-biphenyl]-3-yl)benzo[d]thiazole (denoted as TBBT). Moreover, the computed emission energy of TBBT more closely matches the experimental data compared to TBBT-T. Our theoretical results suggest that the luminescence properties of TBBT are not based on the excited state intramolecular proton transfer (ESIPT). Additionally, frontier molecular orbitals (FMOs) and “hole-electron” analysis reveal that TBBT and TBBT-NO show significant intramolecular charge transfer (ICT) characteristics, which further explain the mechanism of action of fluorescent probes.

Professor Alan Mackay died on 24th February 2025, aged 98 This series of recollections covers the period around 1975 when he worked on tiling patterns using pentagons and met with Roger Penrose, the discoverer of the first aperiodic tiling pattern using only two shapes of tiles. The creation of a computer program to draw the Penrose pattern allowed for the derivation of a diffraction pattern showing ten-fold symmetry, preceding the actual discovery of quasi-crystals by Dan Shechtman a few years later.

Musing over half a century of interactions with Alan Mackay, a rich array of thoughts on past occasions emerges—personal as well as professional—some serious, some playful, and some approaching the bizarre. Browsing through a few of these thoughts, I attempt to illustrate some of those aspects of Alan that have demonstrated to me not just his broad, radical intellectual imagination, but also his generosity and humanity, as well as how the environment of the Birkbeck Crystallography Department and his links with J.D. Bernal were instrumental in enabling his fertile mind to flourish.

A new set of azo-uracil compounds, 1,3-dimethyl-5-(m-R-phenylazo)-6-aminouracil (R = -CH₃ (Uazo 1), -OH (Uazo 2), -COOH (Uazo 3), and -SO₃H (Uazo 4)), was synthesized and characterized using single crystal structure (Uazo 2) and spectroscopic tools. The molecular structure of Uazo 2 is monoclinic with a space group of P 1 21/c1. The compound is planar and possesses E-configuration about -N = N- function. The DFT optimized structures of all the compounds were extracted and found identical in terms of planarity, bond lengths, and bond angles. The DFT study also supports that of the possible isomers the azo-amine form (17.63 kcal/mole) is energetically more stable than the other isomers. The FTIR and ¹H NMR spectra extracted from the optimized structures are well-matched with the experimentally obtained data. In solution, the compounds exist exclusively in an anionic form of hydrazone tautomer, which is supported by the DFT study, by 112.73 kcal/mole. A solvatochromism study provides more insight about the stability of the anionic form of hydrazone in solution. The study of acid–base equilibria was executed with the results of pKa values of the dyes follow as Uazo 2 (pKa 4.98) > Uazo 1 (pKa 4.82) >  > Uazo 3 (pKa 4.2) > Uazo 4 (pKa 4.08). The trend of pKa values is supported by the MEP and NBO studies. The pKa values indicate that the compounds are acid hydrazone dyes.

The study reports a molecular descriptive based design for carbon quantum dots (CQDT) to their photovoltaic (PV) performance. Taking C₃₀H₁₄ as an example, its new molecular systems as CQDT1-CQDT5 are optimized by Density Functional Theory (DFT). Their molecular descriptors are calculated with the help of a Python programming language package RDKit tool. Their Frontier Molecular Orbitals (FMOs) show a charge switching behavior, and UV–Vis analysis shows a redshift of their maximum absorption (λ_max) values. Among their RDKit descriptors, their Bertz Complexity Topology (BertzCT) and molecular connectivity indices (({chi }_{o}^{v})) emerge as important for determining their J_sc. P_max shows positive relation correlation. Further efficiency is analyzed through additional PV parameters while their electronic excitations are visualized using Multiwfn-based Transition Density Matrix (TDM) and electron–hole overlap analysis. This synergy of theoretical and molecular descriptor-related approaches could pave the way for the rational design of high-efficiency CQDTs as PV devices.

Nonlinear optical (NLO) properties of 7-vinyl-4-(4-vinyl-1H-benzo[d]imidazol-7yl)benzo[d]thiazole (BiTh) derivatives have been studied theoretically using DFT and TD-DFT methods. The optical and electronic structure properties of BiTh derivatives, including their frontier molecular orbitals (FMOs), energy band gap (E_g), charge transport and injection properties, excited state properties, and NLO properties, have also been studied in relation to the effects of electron-donating and electron-withdrawing substituents. This study aims to investigate the optical and charge transport characteristics of BiTh derivatives for potential NLO applications. The BiTh derivatives analyzed exhibit a narrower E_g, lower electron reorganization energy (λ_e), higher electron transport rate (K_e), lower absorption energy (E_abs), longer absorption wavelength, and greater hyperpolarizability (β) compared to urea, making them more promising NLO-active materials. Notably, BiTh3 (lowest E_g = 1.78 eV and greatest β = 724.069 × 10⁻³⁰ esu than others) and BiTh2 (lowest λ_e = 0.30 eV, highest K_e = 6.59 × 10¹⁴ s⁻¹, and high β = 553.190 × 10⁻³⁰ esu than others) demonstrate particularly promising optoelectronic properties suitable for NLO applications. 

Graphical Abstract

Charge transfer complexes (CTCs) are widely used in electrical, medicinal, optoelectronic, and other fields. Melamine (MA) as an acceptor and picric acid/quinol (PA/QL) as a donor form [MA(PA)₂] and [MA(QL)₂] proton CTCs. Density functional theory (DFT) was used to investigate the structural properties of these compounds, allowing a more detailed view of intermolecular interactions in CTCs. The structural, optical, and electric properties of titled CTCs based on melamine were investigated using DFT at the B3LYP level with the 6-311G (d, p) basis sets. The frontier molecular orbitals, energy gap (ΔE_H-L), electronegativity (χ), global softness (S), and global electrophilicity index (ω) parameters were obtained to investigate the chemical reactivity of CTCs. The simulated and experimental FTIR and UV–Vis spectra were compared. The reduced density gradient (RDG), natural bonding orbital (NBO), and molecular electrostatic potential (MEP) surfaces were investigated to understand intermolecular interactions. Recent calculation evidence deepens the understanding of CTCs, and their new applications are being exploited.

Structure parameters of (Z)-2-hydroxyridine and 2-pyridone tautomers that coexist under gas-phase conditions are determined with the use of gas electron diffraction (GED) technique accompanied with quantum chemical calculations. In the gas phase, (Z)-2-hydroxyridine is found to be prevailing, and its fraction is gradually decreasing with an increase in temperature. The changes found supplement the data of independent investigations with the use of microwave, infrared, and ultraviolet photoelectron spectroscopies and reveal the probable errors of different methods, which make it necessary to combine different approaches and arrange additional experiments.

The results of the synthesis and investigation of two copper(II) complexes based on 1-phenyl-3-(8-quinolylamino)but-2-en-1-one (HL) are presented. Both complexes were characterized by elemental analysis and IR spectroscopy. The crystalline and molecular structure of copper(II) complexes was determined using single-crystal X-ray diffraction analysis. Depending on the synthesis method (with or without the addition of sodium methoxide in a methanol solution), two different types of crystal structures with compositions CuL₂ and CuLCOOCH₃ were obtained. The Hirschfeld surface analysis method was used to analyze interactions between molecules in crystals, which made it possible to visualize and quantify hydrogen bonds, van der Waals forces, and π-π stacking interactions in these compounds. This study demonstrated that the structure of the complex is dependent on the synthesis conditions that affect the coordination environment of copper(II) ions and the characteristics of intermolecular interaction.