Detailed quantum mechanical studies on bioactive benzodiazepine derivatives and their adsorption over graphene sheets

Theoretical model study of adsorbed antimalarial-graphene dimers: doping effects, photophysical parameters, intermolecular interactions, edge adsorption, and SERS

Future diagnostics and therapy applications are in part riding on the discovery and implementation of new optical techniques and strategies (which often derive from dyads) for example, prediction of features in surface-enhanced Raman spectroscopy requires the study of chromophore-chromophore interactions involve intermolecular forces, drug delivery, and photo mechanisms which are of great interest. New matches between chromophore systems (i.e. FRET), and π-delocalized surfaces are important to study. We explore low-molecular weight drug molecules and their interaction with the reporter material/surface of graphene. Bonding, charge transfer and orbital interactions for 2-amino-5-(1-methyl-5-nitro-2-imidazolyl)-1,3,4-thiadiazole (megazol or AMIT) on graphene were carried out. The graphene model substrate was monotonically/monatomically substituted (doped) with one neutral heteroatom (N/O/S/B) in place of one carbon center; chemical adsorption of AMIT is due to charge transfer from doped graphene to AMIT (DFT). Our AMIT-nanocluster studies show that the nanoclusters will act as a sensor component for the detection of drugs due to SERS. Our findings identified that the greater the energy of the charge transfer, the stronger the calculated chemical adsorption. Additionally, charge transfer is highest for the N-doped systems and least for pristine graphene, resulting in a stronger adsorption energy for N-doped graphene. Mulliken charge analysis of structures confirms enhancement found in QD-AMIT systems.Communicated by Ramaswamy H. Sarma.

A foundational theoreticalAl12E12(E = N, P) adsorption and quinolone docking study: cage–quinolone pairs, optics and possible therapeutic and diagnostic applications

This combined Al₁₂E₁₂ (E = N, P) surface adsorption and docking study describes the new possibility of prospective potential probing(photophysical/optical) and therapy(medicinal/biochemical) with these adsorbent conjugates. DFT investigations were undertaken herein to help generate geometrical models and better understand the possible favorable adsorption energetics. We attempt to explain their adsorption behaviors and docking involving SARS-CoV-2 viruses (PDB)to assess their possible pharmaceutical potential against the pandemic virus (COVID-19). The adsorption behavior of 8-hydroxy-2-methylquinoline (MQ) and its halogenated derivatives, 5,7-diiodo-8-hydroxy-2-methylquinoline (MQI), 5,7-dichloro-8-hydroxy-2-methylquinoline (MQCl), and 5,7-dibromo-8-hydroxy-2-methylquinoline (MQBr), with aluminum-nitrogen (AlN), and aluminum-phosphorous (AlP) fullerene-like nanocages is reported. A decrease in the hardness of the nanoclusters when adsorbed with drug molecules resulted in an incrementally improved chemical softness (see e.g., Hard-Soft Acid Base theory) indicating that reactivity of the drug molecule in the resulting complex increases upon cluster chemical adsorption. The energy gap is found to be maximized for AlN-MQ and minimized for AlP-MQI; the reduced density gradient (RDG) iso-surfaces and AIM studies also corroborated this. Therefore, these two were found, respectively, to be the least and most electrically conductive of the species under study. We selected a simple medicinal building block (chelator)in addition to selecting the cluster based on previous literature reports. Important parameters such as gap energies and global indices were determined. We assessed NLO properties. The SARS-CoV-2 virus PDB docking data for 6VW1, 6VYO, 6WKQ, 7AD1, 7AOL, 7B3C, were enlisted as ligand targets for studies of docking (PatchDock Server) using the requisite PDB geometries (For the structure of 6VW1, kindly see reference, 2020; For the structure of 6VYO kindly see reference, 2020; For the structure of 6WKQ kindly see reference, 2020; For the structure of 7AD1 kindly see reference, 2021; For the structure of 7AOL kindly see reference, 2021; For the structure of 7B3C kindly see reference, 2021). Such findings indicate that the AlN-drug conjugation have inhibitory effect against these selected receptors.Communicated by Ramaswamy H. Sarma.

Evidence of cluster formation of croconic acid with Ag, Au and Cu cages, enhancement of electronic properties and Raman activity

Investigation of the adsorption properties croconic acid (CCA) with metal clusters (mC: Ag, Au and Cu) are reported using DFT method. CCA is found to form stable cluster with transition metal clusters of copper, silver and gold. The drug-cluster complexaton energy is slightly more for the copper nanocluster-drug complex. Non-covalent interaction analysis indicated that strong interactions and weak van der Waal interaction is present between drug and metal clusters. Dipole moment of the drug-gold cluster is found to be higher than that of the other systems. SERS studies demonstrates improved Raman signals for multiple wavenumbers of all CCA-metal cluster complexes. Mulliken charge analysis show that all CCA oxygen atom's charge changes due to the interactions with the mCs. Clustering of CCA with metal cages enhances the medicinal properties and the metal nanoclusters will act as a drug carrier of CCA.

DFT computational study of trihalogenated aniline derivative's adsorption onto graphene/fullerene/fullerene-like nanocages, X12Y12 (X = Al, B, and Y = N, P)

Adsorption of 2,4,6-tribromoaniline (BA), 2,4,6-trifluoroaniline (FA) and 2,4,6-trichloroaniline (CA) onto the surface of coronene/fullerene/fullerene-like nanocages was investigated by theoretical calculations. Due to the adsorption of BA/FA/CA, there are significant changes in chemical descriptors and nonlinear optical properties. Energy gap values of all nanoclusters are lowered, giving an increase in conductivity of complexes except for fullerene. All complex's ultraviolet visible wavenumber is blue-shifted and especially for fullerene complex, the values are very high. The enhancement of Raman intensities shows that it is possible to design a nanocage sensor for detecting these compounds by surface-enhanced Raman scattering (SERS).Communicated by Ramaswamy H. Sarma.

Adsorption of adipic acid in Al/B-N/P nanocages: DFT investigations

Drug delivery clusters based on nanocages recently have been the most capable to study. Adipic acid (ADPA) interaction mechanism over nanocages of X(Al/B)12Y(N/P)12 was investigated. We analyzed various electronic, chemical, and spectroscopic properties with nanocages of the adsorbed ADPA molecule. Adsorption energies were calculated to study the adsorption of ADPA with nanocages. Raman enhanced surface scattering is used to track the drug as an effective approach to vibrational spectroscopy. Detection of the drug has been investigated using the SERS properties of nanocages. Title drug acts as a donor of electrons and adsorbs at the electrophilic site of nanocages. Variations in chemical descriptors to recognize the sensing property of ADPA-nanocages are also noted. Analysis of various properties explains enhancement which makes it possible to detect the drug in other products. • Interaction of adipic acid with fullerene-like metal nanocages • Enhancement of spectral properties • Changes in charge transfer values in nanocage-drug system • Docking studies identify the drug delivery property.

DFT computational study towards investigating psychotropic drugs, promazine and trifluoperazine adsorption on graphene, fullerene and carbon cyclic ring nanoclusters

Detection and qualification process related to impurities assume importance in pharmacological drug development programmes and the present article gives the structural and spectral characterisation of phenothiazine derivatives, promazine (PME) and trifluoperazine (TPE) and their self-assembly with graphene/fullerene/carbon ring (CG/CF/CR) systems theoretically. The investigation of adsorption behaviour of these compounds can provide valuable information about its reactivity, electronic and structural properties. Three-dimensional electrostatic potential diagrams were mapped. The frontier orbital energies and energy band gaps of the molecules were computed. Delocalization of charge density between the bonding or lone pair and antibonding orbitals is calculated by NBO analysis. Docking was executed to investigate binding areas of chemical compounds. Bioactivity scores show that the pharmacokinetic and pharmacological properties of the ligands are appropriate leading to be considered potential drug agents. The obtained theoretical wavenumber results of the present study were fully compatible with the experimental results.

Utilization of O/S-doped graphene nanoclusters for ultrasensitive detection of flurane derivatives-DFT investigations

Nanocluster based drug delivery systems are very useful in modern medical treatment and interaction mechanism of desflurane (DES), isoflurane ISO), sevoflurane (SEV) over carboxyl substituted graphene-doped with O and S atoms were investigated in the present study. Different electronic and chemical properties of adsorbed desflurane, isoflurane and sevoflurane with nanoclusters are analyzed. To track the drugs, SERS is used as an efficient method and drug's detection was analyzed using SERS. DES's energy over GQD-S is greater than that over GQD-O nanocluster and for ISO and SEV, adsorption energies over the O/S nanoclusters are same. The title drugs work on the reactives sites and got adsorbed. For ISO, there is an increase in fluorine atom charges and for DES and SEV, the fluorine atom charge decreases due to adsorption in both O/S nanoclusters. Changes in chemical descriptors are identified for the sensing property of drug-nanoclusters.Communicated by Ramaswamy H. Sarma.

Utilization of doped/undoped graphene quantum dots for ultrasensitive detection of duphaston, a SERS platform

Recently nanocluster based drug delivery systems have become the most skillful to study. Interaction mechanism of duphaston (DPH) over graphene (G), carboxyl substituted graphene (COG) and doped COG-X (X = O/S/N/B) were investigated. We studied different spectroscopic properties of adsorbed DPH with nanoclusters. To study effect adsorption of DPH with nanoclusters, the adsorption energies were measured. To track DPH, surface enhanced Raman scattering is used since it is an efficient approach to vibrational spectroscopy. The DPH detection was investigated using GQDs SERS property. For the adsorption of DPH with COG-B nanocluster maximum energy interaction is determined. DPH works on the electrophilic site of nanoclusters as donor of electrons and adsorbs. Charge transfer is higher for to COG-B nanocluster than for other nanoclusters. Variations in chemical descriptors are also noted to understand sensing property of DPH molecule-nanoclusters. The analysis of different properties demonstrates enhancement effect which makes it significant in detecting DPH in other products.

Conformational analysis and quantum descriptors of two new imidazole derivatives by experimental, DFT, AIM, molecular docking studies and adsorption activity on graphene

1-[2-(2-hydroxy-3-methoxy-5-(4-methoxyphenylazo)benzaldeneamino)ethyl]-3-methyl-3H-imidazole (HMY) and 1-[2-(2-hydroxy-3-methoxy-5-(4-methylphenylazo)benzaldene amino)ethyl]-3-methyl-3H-imidazole (HMM) were synthesized and characterized using spectral analysis. Conformational analysis has been achieved using potential energy scan for different rotable bonds for obtaining the lowest energy conformer. Conformer with minimum energy is obtained along the dihedral angle N30-C31-C34-N37. QTAIM analysis gives nature and strength of hydrogen bonding interactions. UV-Vis, electrostatic potential and chemical descriptors are analyzed. Interaction of HMY and HMM with graphene is analyzed in terms of SERS activity. Chemical reactivity descriptors were investigated for graphene-drug systems. NLO activity of parent drugs and its graphene complexes show good activity. The wavenumber downshift of different modes is noted. Title molecules exhibit inhibitory activity against cytochrome C peroxidase. Interactions with graphene sheets are theoretically predicted for the title compounds.

Spectral analysis and detailed quantum mechanical investigation of some acetanilide analogues and their self-assemblies with graphene and fullerene

Spectroscopic analysis and different quantum mechanical studies of four pharmaceutically active compounds phenacetin, p-acetanisidide, 4'-butoxyacetanilide, and 4'-(3-chloropropoxy)acetanilide are reported in this manuscript. Simulated IR spectrum of these compounds was compared with experimentally available data, and essential functional group assignments were made. We also report the frontier orbital properties and other derived local energy descriptors which talks about the relative stability and reactivity. Photovoltaic efficiency of the compounds was studied from the simulated electronic spectra. The compound was found to interact with graphene and fullerene, to form molecular self-assembly. These self-assemblies showed tremendous enhancement in various physicochemical properties when compared with its constituents. The nature of the interactions between studied chemical species was discussed with the help of chemical reactivity principles. Biological activity of the compounds was predicted using molecular docking studies. It is interesting to see that on adsorption with a graphene/fullerene surface, all adsorbed complex shows enhancement in the Raman activity giving surface enhanced Raman spectra (SERS). This can be used for the detection of these drugs in a pharmacological or biological sample. Interestingly the graphene/fullerene drug molecular assembly shows enhanced biological activity when compared with individual drug molecules. Graphical abstract.