Quantum Theory Of Atoms In Molecules Research Articles

Triazine based fluorescent sensor for sequential detection of Hg2+ and L-Cysteine in real samples and application in logic Gate: A combination of Extensive experimental and theoretical analysis

Triazine based fluorescent sensor TBT was rationally designed and synthesized to achieve sequential detection of Hg2+ and L-cysteine based on the presence of sulfur moiety and suitable cavity in the molecule. Sensor TBT exhibited excellent sensing potential for the selective detection of Hg2+ ions and L-cysteine (Cys) in real samples. Upon addition of Hg2+ to sensor TBT, enhancement in emission intensity of sensor TBT was observed which was accredited to the presence of sulfur moiety and size of cavity in the sensor. Upon interaction with Hg2+ blockage of intramolecular charge transfer (ICT) along with chelation-enhanced fluorescence (CHEF) resulted in the increase in fluorescence emission intensity of sensor TBT. Further, TBT-Hg2+ complex was employed for the selective detection of Cys through fluorescence quenching mechanism. This was attributed to the significantly stronger interaction of Cys with Hg2+, which resulted in the formation of Cys-Hg2+ complex and subsequently sensor TBT was released from TBT-Hg2+ complex. The nature of interaction between TBT-Hg2+ and Cys-Hg2+ complex was evaluated through 1H NMR titration experimentations. Extensive DFT studies were also carried out which include thermodynamic stability, frontier molecular orbitals (FMO), density of states (DOS), non-covalent interaction (NCI), quantum theory of atom in molecule (QTAIM), electron density differences (EDD) and natural bond orbital (NBO) analyses. All the studies supported the non-covalent type of interaction between analytes and sensor TBT. The limit of detection for Hg2+ ions was found to be as low as 61.9 nM. Sensor TBT was also employed for the quantitative detection of Hg2+ and Cys in real samples. Additionally, logic gate was fabricated by using sequential detection strategy.

Gas-Phase Interaction of CO, CO2, H2S, NH3, NO, NO2, and SO2 with Zn12O12 and Zn24 Atomic Clusters.

Atmospheric pollutants pose a high risk to human health, and therefore it is necessary to capture and preferably remove them from ambient air. In this work, we investigate the intermolecular interaction between the pollutants such as CO, CO2, H2S, NH3, NO, NO2, and SO2 gases with the Zn24 and Zn12O12 atomic clusters, using the density functional theory (DFT) at the meta-hybrid functional TPSSh and LANl2Dz basis set. The adsorption energy of these gas molecules on the outer surfaces of both types of clusters has been calculated and found to have a negative value, indicating a strong molecular-cluster interaction. The largest adsorption energy has been observed between SO2 and the Zn24 cluster. In general, the Zn24 cluster appears to be more effective for adsorbing SO2, NO2, and NO than Zn12O12, whereas the latter is preferable for the adsorption of CO, CO2, H2S, and NH3. Frontier molecular orbital (FMO) analysis showed that Zn24 exhibits higher stability upon adsorption of NH3, NO, NO2, and SO2, with the adsorption energy falling within the chemisorption range. The Zn12O12 cluster shows a characteristic decrease in band gap upon adsorption of CO, H2S, NO, and NO2, suggesting an increase in electrical conductivity. Natural bond orbital (NBO) analysis also suggests the presence of strong intermolecular interactions between atomic clusters and the gases. This interaction was recognized to be strong and noncovalent, as determined by noncovalent interaction (NCI) and quantum theory of atoms in molecules (QTAIM) analyses. Overall, our results suggest that both Zn24 and Zn12O12 clusters are good candidate species for promoting adsorption and, thus, can be employed in different materials and/or systems for enhancing interaction with CO, H2S, NO, or NO2.

Electronic and dynamical properties of non-covalent diatomic aggregates formed by He with neutral and ionic Li and Be.

This work aims to study the influence of the absence and presence of permanent charges on the electronic and dynamical properties of the non-covalent bound diatomic systems involving He and Li, Be as neutral and ionic partners. The charge displacement results suggest that in the formation of HeLi[Formula: see text], HeBe[Formula: see text], and HeBe[Formula: see text], the neutral He atom undergoes, in the electric field of the ion, a pronounced electronic polarization, and the natural bond order theoretical approach indicates that in the formation of the molecular orbital He acts as a weak electron donor. The energy decomposition analysis provides the dispersion and induction components as the attractive leading terms controlling the stability of all systems, confirming that the formed bond substantially maintains a non-covalent nature which is also supported by the Quantum Theory of Atoms in Molecules (QTAIM) analysis. Finally, it was found that the HeLi and HeBe neutral systems are unstable under any condition, HeLi[Formula: see text] and HeBe[Formula: see text] ionic systems are stable below 317K and 138K, respectively, while the HeBe[Formula: see text] system becomes unstable only after 3045K. The potential energy curves and interactions in all systems were studied theoretically based on coupled-cluster singles and doubles method with perturbative inclusion of triples CCSD(T) method with an aug-cc-pV5Z basis set. More precisely, it was determined the potential energy curves describing the stability of the HeLi, HeLi[Formula: see text], HeBe, HeBe[Formula: see text], and HeBe[Formula: see text] systems, the charge displacement within the formed adducts, the decomposition of their total interaction energy, the topological analysis of their bonds, their rovibrational energies, their spectroscopic constants and lifetimes.

Probing the hydrogen bond network in the crystal structure of a sulfonamide derivative: A quantum chemical approach

A novel sulfonamide derivative, N-[2-[(5-bromo-2-chloro-4-pyrimidinyl)thio]-4-methoxyphenyl] benzene sulfonamide, was synthesized and characterized using spectroscopic techniques. Single crystal X-ray diffraction analysis determined that the compound crystallizes in the monoclinic crystal system with the space group P21/c with Z = 8. The crystal packing of the compound was found to be largely influenced by N-H···O intermolecular interactions. Hirshfeld surface analysis with fingerprint plots was performed to visualize the intermolecular interactions present in the crystal structure. Density functional theory (DFT) studies were employed to obtain the electronic structure of the compound, including frontier molecular orbitals and their energy gap, molecular electron densities, and electrostatic potential maps. The stability of the molecule, resulting from hyperconjugative interactions and charge delocalization, was analyzed using Natural Bond Orbital (NBO) analysis. Quantum theory of atoms in molecules (QTAIM) and reduced density gradient (RDG) analysis were conducted to explore the weak interactions present in the molecule. Overall, this study provides insight into the hydrogen bonding interactions and crystal packing of sulfonamide derivatives, which have important implications for their properties in various fields such as medicinal chemistry, agrochemicals, and material science.

On the Importance of H-Bonding Interactions in the Enclathration of Boric Acids in Na(I) Polymers: Experimental and Theoretical Studies

Two Na(I) coordination polymers, namely, {Na(BA)2(μ-H2O)2}n{adp}n (1) and {[Na2(μ-BA)(μ-fum)(μ-H2O)4](BA)}n (2) (where, BA = boric acid, adp = adipic acid, fum = fumarate),were prepared and characterized using elemental analysis, TGA, FT-IR, and single-crystal X-ray diffraction techniques. Various unconventional supramolecular interactions, i.e., CH∙∙∙HC and parallel CO∙∙∙CO interactions, stabilize the layered assembly of compound 1. Interesting dual enclathration of BA molecules within the supramolecular host cavities formed by O-H∙∙∙O and C-H∙∙∙C interactions stabilizes the crystal structure of compound 2. The H-bonding interactions in 1 and 2 were further studied theoretically using the quantum theory of atoms in molecules (QTAIM) and the noncovalent interaction plot (NCI Plot) computational tools. The energy of the H-bonds was estimated using the potential energy density at the bond critical points. Theoretical calculations confirmed the presence of O-H∙∙∙O H-bonding interactions in both compounds, forming structure-guiding R22(8) synthons relevant for the stability of the compounds.

New fluorescent probe for sensing of mefenamic acid in aqueous medium: An integrated experimental and theoretical analysis

Abnormal levels of mefenamic acid (MFA) in living organisms can result in hepatic necrosis, liver, and gastrointestinal diseases. Therefore, development of accurate and effective method for detection of MFA is of great significance for the protection of public health. Herein, we designed a stilbene based sensor ECO for the sensitive and selective detection of mefenamic acid by employing fluorescence spectroscopy for the first time. The developed sensor ECO displayed fluorescence turn-off response towards MFA based on PET (photoinduced electron transfer) and hydrogen bonding. The sensing mechanism of MFA was investigated through 1H NMR titration experiment and density functional theory (DFT) calculations. The presence of non-covalent interaction was confirmed through spectroscopic analysis and was further supported by non-covalent interaction (NCI) analysis and Bader’s quantum theory of atoms in molecules (QTAIM) analysis. Additionally, the sensor ECO coated test strips were fabricated for on-site detection of mefenamic acid. Furthermore, the practical applicability of sensor ECO to detect MFA was also explored in human blood and artificial urine samples.

Revealing a notable interaction in the binding of type II statins to HMG‐CoA reductase: Stacked cation–π interaction

AbstractThis study has centered on potentially important enzyme‐ligand interaction currently not incorporated: stacked cation–π interaction between the guanidinium group of arginine 590 residues in the HMG‐CoA reductase active site and the 4‐fluorophenyl group of type II statins. The geometry of interaction between these planar groups has been considered based on the X‐ray crystallographic structures already available in the protein data bank (PDB) archive. Electronic interaction energies between this residue and statins have been acquired by M06 and MP2 methods. In addition, stacking interaction and hydrogen bonding as two important investigated interactions are verified through prominent analyses: (1) quantum theory of atoms in molecules (QTAIM) analysis; (2) plotting and quantitative molecular surface analyses such as electrostatic potential (ESP) analysis, Hirshfeld surface (HS) and Becke surface (BS) analyses; (3) visual study methods such as noncovalent interaction (NCI), independent gradient model (IGM) analyses; and (4) localized orbital locator integrated pi over plane (LOLIPOP) index.The results indicate the absolute binding energy for type II statins is overall more than for type I statins.

Hexachlorobenzene (HCB) adsorption onto the surfaces of C60, C59Si, and C59Ge: Insight from DFT, QTAIM, and NCI

Several reports have shown that nanomaterials have been found to be effective for gas sensing application and the adsorption of hazardous organochloride. Herein, dispersion corrected density functionals; D3-B3LYP-D3, ωB97XD, M06-2X and PBE0 all at the 6-311G (d) basis set was used to study the interactions of metal-doped fullerenes (silicon (C59Si) and germanium (C59Ge)) with Hexachlorobenzene (C6Cl6) gas molecule. The adsorption properties of the adsorbents viz; the pure fullerene nanocage (C60) and the doped system; Silicon (C59Si) and Germanium (C59Ge) were all investigated in terms of reactivity, stability, bond order, intermolecular interaction, van der waals, and weak interaction as well as adsorption energy. The reactivity levels of the examined surfaces were observed within the same range at the B3LYP-D3/6-311G (d) level of theory to be 5.996 eV, 5.309 eV, and 5.188 eV for C60, C59Si and C59Ge adsorbents respectively. From our calculation for adsorption energies; the high negative value -1.010 eV of for the C59Ge nanocage suggests that the doped surface adsorbs hexachlorobenzene better in comparison to the other surfaces and adsorption is thermodynamically favored. The results for natural bond orbitals (NBO), quantum theory of atoms in molecules (QTAIM), and non-covalent interaction (NCI) were consistent across all systems and favored physical adsorption.

Photophysical and nonlinear optical properties of para-substituted nitrobenzofurazan: A comprehensive DFT investigation

We investigate the ability of the 4-chloro-7-nitrobenzofurazan (NBD-Cl) to append Pyrrolidine (Pyrr), a secondary amine, acting as a nucleophile group in SNAr reactions resulting in the fluorescent NBD-Pyrr compound. Their electrochemical and photo-physical responses have been thoroughly investigated using Cyclic Voltammetry (CV), UV–Visible, photoluminescence (cw-PL) and time resolved photoluminescence (TR-PL) spectroscopies. The intra-molecular charge transfer associated to nonlinear optical (NLO) properties of NBD-Pyrr molecule has reported, for the first time. Important NLO parameters such as dipole moment (μ), polarizability (α), anisotropy of polarizability (Δα) and first and second order hyperpolarizabilities (β and γ) are calculated at the B3LYP/6–31 + g(d,p) level of theory as well. Additionally, natural bond orbital (NBO) and quantum theory of atoms in molecules (QTAIM), Hirshfeld surface (HS), Electron Localization Function (ELF), and Localized orbital locator (LOL) analyses have been used to illustrate structure and bonding in the NBD-Pyrr molecule.

Functionalized (–HCO, –OH, –NH2) Iridium-doped graphene (Ir@Gp) nanomaterials for enhanced delivery of Piroxicam: Insights from quantum chemical calculations

Delivery of piroxicam into the body has been associated with various health complications, such as gastrointestinal problems, cardiovascular problems, renal problems, injection site reactions, systemic side effects, drug interactions, and localized tissue damage. In this study, the geometry of Ir@Gp functionalized with OH, HCO, and NH2 was investigated using density functional theory (DFT) at the ωB97XD/def2svp level of theory to determine the system with the best delivery potential for piroxicam. The results of the study showed that all studied systems had an increase in bond length, except for Pxm_NH2_Ir@Gp, which had a decrease in bond length. This suggests that Pxm_NH2_Ir@Gp is reactive to the drug's adsorption and is consistent with the chemical quantum descriptors calculated from frontier molecular orbital (FMO) and natural bond orbital (NBO) analysis. Substantially, the quantum theory of atom in molecules (QTAIM) established that partially covalent interactions were more evident in the Pxm_HCO_Ir@GP and Pxm_OH_Ir@GP systems, while noncovalent interactions were supported by the weakest bonds of the interaction at H65-H98 and H92-H64, respectively. The findings of the non-covalent interactions (NCI) further affirmed that the effectiveness of the drug's delivery to target sites depended on the presence of weak interactions between the studied systems. The calculated Eads calculated in the gas phase showed that weak chemical binding of the drug towards the adsorbent was obtained in Pxm_Ir@GP, Pxm_OH_Ir@GP, and Pxm_HCO_Ir@GP. Whereas, in the water phase, the adsorption energy values for all complexes (pxm_Ir@GP) were mostly negative, indicating that the water molecules energetically favor the adsorption of the drug onto the surfaces studied than the gas-phase. Among the water-phase complexes, pxm_Ir@GP revealed the highest negative adsorption energy of −5.116 eV, indicating that it has the highest affinity for water. This result, which corresponds with other analyses in this study, shows that Pxm_NH2_Ir@GP can be used as an efficient material for the effective carriage of pirixocam to the target cells in both gas and water phase. Overall, it can be said that the systems' adsorption efficiency is as follows: pxm_Ir@GP > pxm_NH2_Ir@GP > pxm_OH_Ir@G. Summarily, this results which undoubtedly corresponds with other analysis in this study shows that pxm_NH2_Ir@GP (in both gas and water phase), can be used as an efficient and sensitive biosensor material for the effective carriage of pxm drug to bio cells.

DFT study of the adsorption of simple organic sulfur gases on g-C3N4; periodic and non-periodic approaches

In the present work, the adsorption of some simple organic sulfur gases (CS2, OCS, and CH3SH) on the g-C3N4 was studied using periodic and non-periodic density functional theory (DFT). PBE-D3/DNP and B3LYP-D3/6-31G(d) levels of theory were employed for periodic and non-periodic calculations, respectively. The calculated CS2, OCS, and CH3SH adsorption energies were obtained to be −4.35, −5.82, and −8.58 Kcal/mol. The interactions of simple organic sulfur gases with g-C3N4 were characterized by NBO second-order perturbation theory and quantum theory of atom in molecule (QTAIM). The bandgap energies and work function of g-C3N4 and its complexes with simple organic sulfur gases were extracted from their band structures. The CS2 and OCS adsorptions didn’t significantly alter the bandgap and work function of g-C3N4. Therefore, g-C3N4 is not a proper sensor for detecting CS2 and OCS. The bandgap and work function of g-C3N4 were averagely changed by 18% and 2.7%, respectively, after CH3SH adsorption. Accordingly, g-C3N4 may use as a suitable sensor for detecting CH3SH based on electronic conductivity and work function.

A Theoretical Investigation of Chemical Bonding of a Heterometallic Trinuclear Cluster Containing Iridium and Ruthenium: [(Cp*Ir) (CpRu)2 (μ3-H) (μ-H)3] by QTAIM Approach

Numerous integral and local electron density’s topological parameters of significant metal-metal and metal-ligand bonding interactions in a trinuclear tetrahydrido cluster [(Cp* Ir) (Cp Ru)2 (μ3-H) (μ-H)3]1 (Cp = η5 -C5Me5), (Cp* = η5 -C5Me4Et) were calculated and interpreted by using the quantum theory of atoms in molecules (QTAIM). The properties of bond critical points such as the delocalization indices δ (A, B), the electron density ρ(r), the local kinetic energy density G(r), the Laplacian of the electron density ∇2ρ(r), the local energy density H(r), the local potential energy density V(r) and ellipticity ε(r) are compared with data from earlier organometallic system studies. A comparison of the topological processes of different atom-atom interactions has become possible thanks to these results. In the core of the heterometallic tetrahydrido cluster, the Ru2IrH4 part, the calculations showed that there are no bond critical points (BCPs) or identical bond paths (BPs) between Ru-Ru and Ru-Ir. The distribution of electron densities is determined by the position of bridging hydride atoms coordinated to Ru-Ru and Ru-Ir, which significantly affects the bonds between these transition metal atoms. On the other hand, the results confirm that the cluster under study contains a 7c–11e bonding interaction delocalized over M3H4, as shown by the non-negligible delocalization index calculations. The small values for ρ(b) above zero, together with the small values, again above zero, for Laplacian ∇2ρ(b) and the small positive values for total energy density H(b), are shown by the Ru-H and Ir-H bonds in this cluster is typical for open-shell interactions. Also, the topological data for the bond interactions between Ir and Ru metal atoms with the C atoms of the cyclopentadienyl Cp ring ligands are similar. They show properties very identical to open-shell interactions in the QTAIM classification.

Structure Guiding Supramolecular Assemblies in Metal-Organic Multi-Component Compounds of Mn(II): Experimental and Theoretical Studies

Two multi-component coordination compounds of Mn(II), viz. [Mn(H2O)6](2-Mepy)2(4-NO2bz)2·2H2O (1) and [Mn(H2O)6][Mn(2,3-PDCH)3]2 (2) (where, 2-Mepy = 2-methylpyridine, 4-NO2bz = 4-nitrobenzoate, 2,3-PDC = 2,3-pyridinedicarboxylate), have been synthesized and characterized using elemental, spectroscopic (FT-IR and electronic), TGA and single-crystal X-ray diffraction analyses. Complex 1 is a co-crystal hydrate of Mn(II) involving uncoordinated 2-Mepy, 4-NO2bz and water molecules; while compound 2 is a multi-component molecular complex salt of Mn(II) comprising cationic [Mn(H2O)6]2+ and anionic [Mn(2,3-PDCH)3]−complex moieties. The uncoordinated 2-Mepy and 4-NO2bz moieties of 1 are involved in lone-pair (l.p)-π and C–H⋯π interactions which stabilize the layered assembly of the compound. The crystal structure of compound 2 has been previously reported. However, we have explored the unusual enclathration of complex cationic moieties within the supramolecular host cavities formed by the molecular assembly of complex anionic moieties. The supramolecular assemblies obtained in the crystal structure have been further studied theoretically using DFT calculations, quantum theory of atoms-in-molecules (QTAIM) and non-covalent interaction plot (NCI plot) computational tools. Theoretical studies reveal that the combination of π-staking interactions (l.p-π, π-π and C–H···π) have more structure-guiding roles compared to the H-bonds. The large binding energy of π-stacking interactions in 2 is due to the antiparallel orientation of aromatic rings and their coordination to the metal centers, thereby increasing the contribution of the dipole–dipole interactions.

Fluorine versus Hydroxyl in Supramolecular Space: Effect of Organic Fluorine in Molecular Conformation, Lattice Cohesive Energies, and Receptor Binding in a Series of α-Fluoroketones

We examine the effect of organic fluorine in the molecular conformation and supramolecular packing in a series of α-fluoroketones in comparison to the analogous α-hydroxyketones. Crystal structures of a series of seven α-fluoroketone analogues have been analyzed using single-crystal XRD, and their crystal-packing features have been investigated using a variety of computational tools. Analysis of molecular conformations in this series of α-fluoroketone structures, along with conformational energy scans, revealed a preference for a near-antiperiplanar conformation for α-fluoroketones as opposed to a syn conformation in their α-hydroxy analogues. A quantitative analysis of intermolecular interaction motifs such as C–H···F, C–H···O, C–H···π, C–F···π, etc. in terms of interaction energies and electron density topological parameters from a QTAIM (quantum theory of atoms in molecules) approach reveal their relative strengths and distance dependence. Electron localization function (ELF) and deformation density maps bring out the electrostatic nature of weak interactions involving organic fluorine. Lattice energy values estimated using the CE-B3LYP method show dominant contributions from dispersion in all these structures, which are around 3–4-fold higher than the electrostatic contribution. While the lattice energy values of the α-fluoroketones are found to be lower than those of their hydroxy analogues, a molecular docking study with a common protein receptor site reveals comparable docking scores for α-fluoroketones with respect to the analogous α-hydroxyketones.

Chalcogen Bonds, Halogen Bonds and Halogen···Halogen Contacts in Di- and Tri-iododiorganyltellurium(IV) Derivatives

In this manuscript, we have examined the CSD (Cambridge Structural Database) to investigate the relative ability of Te and I (in practice, the heaviest chalcogen and halogen atoms) in di- and tri-iododiorganyltellurium(IV) derivatives to establish σ-hole interactions. The geometry around the Te(IV) in this type of compound is trigonal bipyramidal where the stereoactive lone pair at Te(IV) occupies one of the equatorial positions. In the solid state, Te(IV) tends to form pseudo-octahedral coordination by establishing strong noncovalent interactions opposite to the two covalent bonds of the equatorial plane. Such contacts can also be classified as chalcogen bonds following the recommendation of the International Union of Pure and Applied Chemistry (IUPAC). Such contacts have been analyzed energetically in this work using density functional theory (DFT) calculations, rationalized using molecular electrostatic potential (MEP) surface analysis and characterized using a combination of the quantum theory of atoms in molecules (QTAIM) and noncovalent interaction plot (NCIplot) computational tools. Finally, the observation of halogen bonds and type I halogen···halogen contacts is also emphasized and compared to the chalcogen bonds. Energy decomposition analysis has also been performed to compare the physical nature of chalcogen, halogen and type I interactions.

A dispersion-corrected DFT calculation on encapsulation of favipiravir drug used as antiviral against COVID-19 into carbon-, boron-, and aluminum-nitride nanotubes for optimal drug delivery systems combined with molecular docking simulations.

The online version contains supplementary material available at 10.1007/s11224-023-02182-4.

Enhanced Am/Eu separation ability of disulfonated diamide N-heterocyclic ligands by adjusting N-, O-donor affinity: A theoretical comparative study

Separation of minor actinides (MAs) from lanthanides (Ln) is a vital and challenging stage in advanced nuclear waste treatment. Development of water-soluble back-extraction ligand is regarded as a feasible alternative method for high efficiency An(III)/Ln(III) separation. Therefore, theoretical investigating on the deep mechanism behind the selective back-extraction of An(III) is very important. In this work, Am- and Eu-complexes with three water-soluble disulfonated N-heterocyclic ligands, disulfonated N,N’-diphenyl-2,9-diamide-1,10-phenanthroline (DS-Ph-DaPhen, L1), disulfonated N,N’-diphenyl-2,9-diamide-2,2′-Dipyridine (DS-Ph-DADipy, L2), and disulfonated N,N’-diphenyl-2,9-diamide 5H-cyclopenta[2,1-b:3,4-b’]-Dipyridine (DS-Ph-Da-5H-Cyclo-PentaDipy, L3) were systematically investigated using quasi-relativistic density functional theory (DFT) method. Electrostaic potential (ESP) and restrained electroStatic potential (RESP) atomic charge on donor atoms indicate that N atoms’ affinity toward metal ions in L2 and L3 was increased by replaceing the phenanthroline ring with dipyridine ring and 5H-Cyclo-PentaDipyridine ring, while the affinity of O atoms seem to decrease from L1 to L2 and L3. Through Wiberg bond indices and quantum theory of atoms in molecule (QTAIM) analyses, three ligands’ Am(III) preference may be attributed to the weak but different extend partial covalency in Am-N and Eu-N bonds. Based on the NBO population and PDOS analyses, slightly more overlap of Am-5f and N/O-2p orbitals than those between Eu-4f and N/O-2p orbitals. Based on the theoretical calculation, the covalency difference between Am-N and Eu-N bonds seems to have inverse correlation with the intensity of M−N bonds. However, all the theoretical results suggest that, by increasing N’s affinity and weakening O’ affinity at the same time, ligand’s Am(III)/Eu(III) separation ability can be improved. This work offers some useful information for changing ligands’ An(III)/Ln(III) back-extraction and separation abilities by adjusting the affinity of donor N and O atoms in its central N-heterocyclic skeleton, and may shed light for future designing of more efficient An(III)/Ln(III) back-extraction ligands.

A computational assessment of the interaction of 5Fluorouracil (5FU) drug connected to B12P12 and ScB11P12 nanocages with adenine nucleobase: DFT, AIM, TD-DFT study

Intelligent transfer of drugs to target cells is one of the important challenges in pharmaceuticals and disease treatment. Based on this, various investigations have been done on the interaction of drugs with different materials and compounds, among which nanomaterials have received more attention due to their wide active surface. In this context, the interaction of 5Fluorouracil (5FU) drug connected B12P12 and ScB11P12 nanocages with the adenine nucleobase is investigated. The results of this study could provide a new idea about the effect of nanocages on drug binding to nucleobase. The computational studied base on the density functional theory at the ωB97XD/6-31G (d, p) level of theory is fulfilled in presence of a static electric field (SEF) in the z-direction (z + 0.01, z + 0.02, z + 0.03, and z + 0.04 au). The outcomes of this study confirm that the interaction of 5FU&B12P12 and 5FU&ScB11P12 complexes with adenine is exothermic and favorable. The electron localized field (ELF) plots, quantum theory of atom in molecule (QTAIM) outputs, and reduced density gradient (RDG) scatter plots have been computed and results are analyzed. The output results demonstrated that the nature of bonding between 5FU&B12P12, and 5FU&ScB11P12 complexes with adenine is electrostatic type. The Eg of all studied complexes change in the range of 5.08 to 6.95 eV and the ∆Eg% is in the range of ‒5.84 to 12.51%. The results of this study recommended that the doping Sc atom and electrical field application increase the interaction of 5FU-drug&B12P12 nanocage with adenine and it is an efficient system for 5FU drug delivery toward target cells.

Scoring molecular wires subject to an ultrafast laser pulse for molecular electronic devices.

A nonionizing ultrafast laser pulse of 20-fs duration with a peak amplitude electric-field ±E = 200 × 10-4 a.u. was simulated. It was applied to the ethene molecule to consider its effect on the electron dynamics, both during the application of the laser pulse and for up to 100 fs after the pulse was switched off. Four laser pulse frequencies ω = 0.2692, 0.2808, 0.2830, and 0.2900 a.u. were chosen to correspond to excitation energies mid-way between the (S1 ,S2 ), (S2 ,S3 ), (S3 ,S4 ) and (S4 ,S5 ) electronic states, respectively. Scalar quantum theory of atoms in molecules (QTAIM) was used to quantify the shifts of the C1C2 bond critical points (BCPs). Depending on the frequencies ω selected, the C1C2 BCP shifts were up to 5.8 times higher after the pulse was switched off compared with a static E-field with the same magnitude. Next generation QTAIM (NG-QTAIM) was used to visualize and quantify the directional chemical character. In particular, polarization effects and bond strengths, in the form of bond-rigidity vs. bond-flexibility, were found, for some laser pulse frequencies, to increase after the laser pulse was switched off. Our analysis demonstrates that NG-QTAIM, in partnership with ultrafast laser irradiation, is useful as a tool in the emerging field of ultrafast electron dynamics, which will be essential for the design, and control of molecular electronic devices.

Synthesis, structural and spectral investigations of an optically active E-N′-(3,4-dimethoxybenzylidene)− 4-fluorobenzohydrazide crystal

Hydrazines represent a group of compounds with pronounced pharmacological activities, along with their possible use of optically active materials. In this contribution, E-N′-(3,4-dimethoxybenzylidene)− 4-fluorobenzohydrazide (DBF) was synthesized and chemically characterized by X-ray crystallography, IR, Raman, UV–VIS, and NMR spectroscopies. The intermolecular interactions governing the stability of the crystal were investigated by the Hirshfeld surface analysis. The structure optimization was performed starting from a crystallographic one. The highest resemblance between experimental and theoretical bond lengths and angles was obtained for the structure at M06–2X/6–311 + +G(d,p) level of theory. The Natural Bond Orbital (NBO) and Quantum Theory of Atoms in Molecules (QTAIM) analyses outlined the most important intramolecular interactions. The IR and Raman spectra vibrational peaks were assigned based on the Potential Energy Distribution (PED) analysis. Theoretical methods with high correlation factors and low mean absolute error reproduced the NMR chemical shifts. The excited state optimization of DBF with a difference of several nm modelled the peak at 330 nm in the experimental UV–VIS spectrum. The Condensed Fukui functions outlined the most active positions for electrophilic, neutrophilic, and radical attacks. The non-linear optical (NLO) Z-scan experiment determined the absorption coefficient and nonlinear refractive index, concluding that DBF can be used as NLO material. The ECOSAR prediction of toxicity showed that the material could be potentially dangerous for aquatic organisms.