Structural, electronic and spectral properties of carborane-containing boron dipyrromethenes (BODIPYs): A first-principles study

The First Discovery of Spherical Carborane Molecular Ferroelectric Crystals

Carborane compounds, known for their exceptional thermal stability and non-toxic attributes, have garnered widespread utility in medicine, supramolecular design, coordination/organometallic chemistry, and others. Although there is considerable interest among chemists, the integration of suitable carborane molecules into ferroelectric materials remains a formidable challenge. In this study, we employ the quasi-spherical design strategy to introduce functional groups at the boron vertices of the o-carborane cage, aiming to reduce molecular symmetry. This approach led to the successful synthesis of the pioneering ferroelectric crystals composed of cage-like carboranes: 9-OH-o-carborane (1) and 9-SH-o-carborane (2), which undergo above-room ferroelectric phase transitions (Tc) at approximately 367 K and 347 K. Interestingly, 1 and 2 represent uniaxial and multiaxial ferroelectrics respectively, with 2 exhibiting six polar axes and as many as twelve equivalent polarization directions. As the pioneering instance of carborane ferroelectric crystals, this study introduces a novel structural archetype for molecular ferroelectrics, thereby providing fresh insights into the exploration of molecular ferroelectric crystals with promising applications.

Design, Synthesis, and Evaluation of Near-Infrared Fluorescent Molecules Based on 4H-1-Benzopyran Core

A series of novel fluorescent 4H-1-benzopyrans was designed and developed as near-infrared fluorescent molecules with a compact donor–acceptor-donor architecture. Spectral intensity of the fluorescent molecules M-1, M-2, M-3 varied significantly with the increasing polarities of solvents, where M-3 showed high viscosity sensitivity in glycerol-ethanol system with a 3-fold increase in emission intensity. Increasing concentrations of compound M-3 to 5% BSA in PBS elicited a 4-fold increase in fluorescence intensity, exhibiting a superior environmental sensitivity. Furthermore, the in vitro cellular uptake behavior and CLSM assay of cancer cell lines demonstrated that M-3 could easily enter the cell nucleus and bind to proteins with low toxicity. Therefore, the synthesized near-infrared fluorescent molecules could provide a new direction for the development of optical imaging probes and potential further drugs.

Spectroscopic and quantum/classical mechanics based computational studies to compare the ability of Andrographolide and its derivative to inhibit Nitric Oxide Synthase

The inhibition of the enzyme Nitric Oxide Synthase by a bioactive compounds results in it possessing anti-inflammatory property. The ability of Andrographolide and its derivative Isoandrographolide to inhibit Nitric Oxide Synthase was studied using computational and experimental techniques. A combination of UV Spectroscopic and DFT computational techniques were used to calculate the molecular descriptors of the title compounds which were used to establish relationship with its biological activity. The drug-likeness of the compounds was estimated using Lipinski's rule. Molecular dynamics and docking studies were carried out to test for the structural and energetic favourability of the title compounds(ligand) being bound to Nitric Oxide Synthase(Protein) to induce inhibition. The force constant data obtained from IR spectroscopy was used in aid to parametrize force fields used in molecular dynamics simulation. The DFT method was used to perform NBO analysis that revealed the charge transfer interactions responsible for its biological properties. The Molecular Electrostatic Potential (MEP) plot revealed the regions of electrophilic and nucleophilic reactivity of the title compounds. MTT (3-(4, 5-dimethyl thiazolyl-2)-2, 5-diphenyltetrazolium bromide) assay was carried out which revealed the cytotoxicity at different concentrations of the title compounds by which means the biologically safe concentration was determined and therefore at this biologically safe concentration the ability of the compounds to inhibit Nitric Oxide formation was determined. Quantitative Structure-Activity Studies (QSAR) were used to furnish relationship between molecular descriptors and the Nitric Oxide Synthase inhibition activity resulting in anti-inflammatory property, based on the chosen molecular descriptors suggestions were made for the search of more potent Nitric Oxide Synthase inhibitors in the Andrographolide derivative family of compounds.

Spectroscopic properties and activated mechanism of NO on isolated cationic tantalum clusters: A first-principles study

The adsorption and dissociation of NO on the cationic Ta₁₅⁺ cluster were investigated using the density-functional theory (DFT) calculations, and the Ta-centered bicapped hexagonal antiprism (BHA) structure of cationic Ta₁₅⁺ cluster can be identified as the global minimum, which reproduces well the infrared multiple photo dissociation (IR-MPD) spectrum. Our results show that the cationic BHATa₁₅⁺ cluster provides the hollow region for NO to interact effectively, and possess larger adsorption strength on the region than other sites. The density of states, charge density differences and frontier molecular orbitals were analyzed to understand the electronic properties of the stable NO-adsorbed isomers. The characteristic IR peaks of the firstly two low-lying isomers are properly assigned, in which the strongest IR peak originates from the N - O stretching vibration. For the dissociation of NO on the BHATa₁₅⁺ cluster, it is found that the reaction path II easily occurs rather than path I due to small reaction barrier, and the cluster may possess the great catalytic behavior to dissociate NO molecule. The present results will inevitably stimulate future theoretical and experimental studies for the design of novel Ta-based catalytic materials for the NO dissociation.