Structural and Solid-State Properties of a Hydrogen-Bonded Pentanedioic Acid–Thiourea Co-Crystal Helen Merina Albert, SK. Fakruddin Babavali, Archana Asatkar, R. Priya, N. R. Rajagopalan, V. Nagalakshmi, Nellore Manoj Kumar, V. Balachandar Physics of the Solid State, 2026 Pentanedioic acid-thiourea (PAT), a new hydrogen-bonded organic co-crystal, was produced using a slow evaporation method and examined for its structural and solid-state properties. Single-crystal X‑ray diffraction confirmed an orthorhombic Pnma structure, stabilized by N–H···O and O–H···S hydrogen-bonding frameworks. The FTIR spectrum validated the functional groups and successful co-crystallization. Optical absorption analysis revealed a strong UV band at 232 nm, a sharp cutoff at 298 nm, and a wide bandgap of 4.165 eV, showing UV-filtering and semiconducting properties. The low Urbach energy (0.085 eV) indicated that the material was well-crystallized and had fewer defects. Dielectric tests revealed temperature and frequency-dependent behavior, with AC conductivity following a thermally activated hopping process. Thermal investigation revealed a multi-stage decomposition process, with stability up to 126°C. Thus, the remarkable solid-state properties of PAT co-crystal make it a suitable material for optoelectronic and UV-filtering uses.
Enhanced 311 nm (NB-UVB) Emission in Gd2O3-Doped Pb3O4-Sb2O3-B2O3-Bi2O3 Glasses: A Promising Platform for Photonic and Medical Phototherapy Applications Valluri Ravi Kumar, P. E. S. Bhaskar, K. Kiran Kumar, V. Sujatha, V. Nagalakshmi, V. Geetha, L. Vijayalakshmi, Jiseok Lim Photonics, 2025 A novel series of Gd2O3-doped Pb3O4–Sb2O3–B2O3–Bi2O3 glasses was synthesized via the conventional melt-quenching technique to explore their structural, thermal, and optical properties for potential photonic and medical phototherapy applications. X-ray diffraction and SEM analyses confirmed the amorphous and homogeneous nature of the samples, while their FTIR spectra revealed characteristic Pb–O, Sb–O, Bi–O, and B–O vibrational bands indicative of a stable glass network. Differential scanning calorimetry (DSC) demonstrated good thermal stability, suitable for high-temperature optical applications. Optical absorption and emission studies indicated the presence of prominent Gd3+ ion transitions, with a strong and sharp ultraviolet emission at 311 nm (6P7/2→8S7/2) when excited at 274 nm. The emission intensity and lifetime increased with Gd2O3 concentrations of up to 1.0 mol%, beyond which concentration quenching was observed. The optimized composition exhibited a reduced optical band gap and enhanced NB-UVB emission efficiency, suggesting efficient energy transfer with minimal non-radiative losses. These results establish the designed glass system as a promising multifunctional material for NB-UVB-based phototherapy, UV-laser generation, scintillation, and other next-generation photonic devices.
Investigation of the Optical, Thermal, Dielectric, Electrical, and Impedance Features of Zinc-Doped Urea-L-Malic Crystals Helen Merina Albert, SK. Fakruddin Babavali, Bonu Akkayya, D. Neelima Patnaik, Maddikera Kalyan Chakravarthi, V. Nagalakshmi, N. R. Rajagopalan Physics of the Solid State, 2025 Abstract Urea-L-malic acid crystals doped with zinc (II) (Zn:ULM) were grown through the process of gradual evaporation. From the X-ray diffraction (XRD) study it was found that the Zn:ULM structure relates to a monoclinic crystal symmetry. UV-visible analysis indicated that the Zn:ULM is incredibly transparent in the UV-visible range with a bandgap of 4.95 eV. According to Kurtz and Perry measurements, the Zn:ULM produced second harmonics 2.25 times that of the potassium dihydrogen phosphate (KDP) value. Thermogravimetric and differential scanning calorimetry (TG-DSC) methods were deployed to assess the thermal stability of Zn:ULM. The dielectric parameters of Zn:ULM were assessed within the 100 Hz to 5 MHz range. Jonscher’s theory was used to explain the mechanisms underlying electrical conductivity. We used impedance spectroscopy to gain more insight into the conductivity process. The findings show that the Zn:ULM crystals are appropriate for optoelectronic uses.
Computational Analysis of Organic Reaction Mechanisms Using DFT: Exploring the Catalytic Efficiency of Transition Metal Complexes Dinesh, K. Kiran Kumar, V. Nagalakshmi, Sandhyashree Rohith, Sindhu. B, M. Jyothi Proceedings of 2025 10th International Conference on Science Technology Engineering and Mathematics Iconstem 2025, 2025 This paper presents the Density Functional Theory (DFT) of catalytic efficiency of transition metal complexes in the organic reaction mechanisms. DFT, which is a quantum mechanical modeling method is used to research the electronic structure, reaction pathways, and the activation energies of the intermediates and transition states in the catalytic cycle that are important. In particular, the Gaussian 16 software is applied in the optimization of the catalyst and reactants geometry, and energy profiles along the reaction coordinate are obtained. The catalyst is represented by the transition metal complex and different organic reaction reactions are investigated to determine the efficiency and stability of the catalyst. The experiment aims at evaluating the energies of activation and intermediates of the reaction; this will make it possible to have a closer insight into the reaction mechanism of the catalytic reaction. Through these computational findings, the research will offer information on how to design more efficient catalysts toward organic transformations which will potentially increase the catalytic performance in an industrial setting.
In silico molecular docking study and nano TiO2-SiO2 catalyzed microwave facilitated synthesis of new bis(α-aminophosphonates) as potential anti-diabetic agents Mahankali Pavan Phani Kumar, Anuradha Vejendla, C. Gladis Raja Malar, Subramanyam Chennamsetty, Subrahmanyam Talari, Nagalakshmi Vedula Phosphorus Sulfur and Silicon and the Related Elements, 2023 AbstractIn the present work, we have developed a greener approach to synthesize a series of novel bis(α-aminophosphonates) (bis(α-Aps)) via a microwave-mediated nano TiO2-SiO2 catalyzed Kabachnik-Fields (K-F) reaction under solvent-free conditions. An in silico molecular docking analysis was performed on all the designed molecules prior to their synthesis to get insight into their capacity to block the enzymes, α-amylase (PDB ID:3IJ8) and α-glucosidase (PDB ID:1OBB). The molecules with significant binding affinity were synthesized and spectroscopically analyzed to confirm their structure. They were screened further in vitro for their inhibitory activity on the target enzymes. When compared with the reference drug, the compounds diethyl[(2H‐1,3‐benzodioxol‐5‐yl)[(6‐{[(2H‐1,3‐benzodioxol‐5‐yl)(diethoxyphosphoryl)-methyl]amino}‐10,10‐dioxo‐9H‐10λ6‐thioxanthen‐3‐yl)amino]-methyl]phosphonate (4h), diethyl [(anthracen-9-yl)[(6-{[(anthracen-9-yl)(diethoxyphosphoryl)methyl]amino}-10,10-dioxo-9H-10λ6-thioxanthen-3-yl)amino]-methyl]phosphonate (4i) have shown greater inhibition, and diethyl{[(6‐{[(diethoxyphosphoryl)(phenyl)methyl]amino}‐10,10‐dioxo‐9H‐10λ6‐thioxanthen‐3‐yl)amino](phenyl)methyl}phosphonate (4a), diethyl {[(6-{[(diethoxyphosphoryl)(4-hydroxy-3-nitrophenyl)methyl]amino}-10,10-dioxo-9H-10λ6-thioxanthen-3-yl)amino](4-hydroxy-3-nitrophenyl)methyl}phosphonate (4e) have shown equal inhibition against the α-amylase enzyme. Compounds diethyl{[(6‐{[(diethoxyphosphoryl)(phenyl)methyl]amino}‐10,10‐dioxo‐9H‐10λ6‐thioxanthen‐3‐yl)-amino](phenyl)methyl}phosphonate (4a), diethyl[(2H‐1,3‐benzodioxol‐5‐yl)[(6‐{[(2H‐1,3‐benzodioxol‐5‐yl)(diethoxyphosphoryl)methyl]amino}‐10,10‐dioxo‐9H‐10λ6‐thioxanthen‐3‐yl)amino]methyl]phosphonate (4h), and diethyl [(anthracen-9-yl)[(6-{[(anthracen-9-yl)(diethoxyphosphoryl)methyl]amino}-10,10-dioxo-9H-10λ6-thioxanthen-3-yl)amino]-methyl]phosphonate (4i) have shown superior inhibition and diethyl{[(6‐{[(diethoxyphosphoryl)(naphthalen‐1‐yl)methyl]amino}‐10,10‐dioxo‐9H‐10λ6‐thioxanthen‐3‐yl)amino](naphthalen‐1‐yl)methyl}phosphonate (4 g) has shown equal inhibition against the α-glucosidase enzyme. All the remaining compounds displayed modest to good inhibition when compared with the reference drug, Acarbose.Keywords: Bis(α-aminophosphonates)nano TiO2.SiO2microwaveKabachnik-Fields reactionα-amylaseα-glucosidase enzyme AcknowledgmentsAuthors acknowledge Dr. S. Someswar Rao, Department of Genitics, Osmania University for his support in bioactivity studies and Dr. C. Naga Raju, Department of Chemistry, S. V. University, Tirupati for his constant support to complete this work.Disclosure statementNo potential conflict of interest was reported by the authors.
Ultrasound mediated nano ZnO catalyzed synthesis of new α-aminophosphonates as potential anti-diabetic agents; an in silico ADMET, molecular docking study, α-amylase and α-glucosidase inhibitory activity CH. Subramanyam, K. Kiran Kumar, K. Venkata Ramana, C. Gladis Raja Malar, S. Mohan, V Nagalakshmi Synthetic Communications, 2023 A more efficient and ecologically friendly method has been devised for the preparation of α-amino phosphonates by Kabachnik-Fields (K-F) reaction in a solvent-free environment using an ultrasonication technique catalyzed by nano ZnO. Primarily, an in silico ADMET and molecular docking analysis was carried out on each molecule prior to synthesis to get insight into drug-likeliness behavior and their capacity to inhibit α-amylase and α-glucosidase. The structure of the newly synthesized compounds was confirmed using spectroscopic analysis, and each one’s in vitro inhibitory action against α-amylase and α-glucosidase was evaluated. The compounds diethyl (4-(4-oxo-4H-chromen-2-yl)phenylamino)(4-hydroxy-3-nitrophenyl)methylphosphonate (7e) and diethyl (4-(4-oxo-4H-chromen-2-yl)phenylamino)(benzo[d][1,3]dioxol-6-yl)methylphosphonate (7h) exhibited the highest inhibitory activity against α-amylase in comparison to the reference substance acarbose. The compounds diethyl (4-(4-oxo-4H-chromen-2-yl)phenylamino)(4-fluorophenyl)methylphosphonate (7d), diethyl (4-(4-oxo-4H-chromen-2-yl)phenylamino)(3-(trifluoromethyl)phenyl)methylphosphonate (7 g) and diethyl (4-(4-oxo-4H-chromen-2-yl)phenylamino)(benzo[d][1,3]dioxol-6-yl)methylphosphonate (7h) have shown the highest inhibitory activity against α-glucosidase than the reference drug, Acarbose. The remaining compounds have shown equipotent to good inhibitory activity against both the tested enzymes. Graphical Abstract
Optimization of WEDM Process Parameters in Al2024-Li-Si3N4MMC K. Raju, M. Balakrishnan, D. V. S. S. S. V. Prasad, V. Nagalakshmi, Pravin P. Patil, S. Kaliappan, B. Arulmurugan, K. Radhakrishnan, B. Velusamy, Prabhu Paramasivam, A. El-Denglawey Journal of Nanomaterials, 2022
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