Quantum Theory Of Atoms In Molecules Research Articles

Theoretical study on the capture of toxic gases by ionic liquids encapsulated in assembled belt[14[pyridine

In the current study, self-assembled belt[14]pyridine (BP) encapsulated IL (tetramethylammonium chloride (TMACl)) is theoretically explored to capture greenhouse gases (GHGs) at B3LYP-D3/6-311G(d,p) level of theory. The encapsulation of TMACl in assembled belt[14]pyridine is thermodynamically feasible as revealed through high interaction energy value of −50.7 kcal/mol. Moreover, the results of capturing of gas molecules (SO2, CO2, CO and CH4) show that attractive forces involved in capturing of gases are strong van der Waals forces i.e., London dispersion forces and electrostatic interactions. The synergic effect of self-assembled belts and ionic liquid results in significantly high interaction energy values ranging from −7.88 to −25.92 kcal/mol for capturing of gas molecules. Furthermore, the interaction between BP-TMACl and gas molecules is studied in detail through natural bond orbital (NBO) analysis. NBO results show the charge transfer between the fragments (BP-TMACl and gases) which is further validated through EDD analysis. The charge shifts towards all of the captured gas molecules but the most prominent change in NBO charges is shown by captured SO2. The successful charge transfer indicates better interaction in the designed systems. Additionally, the type and strength of interactions involved in the process of encapsulation is studied through quantum theory of atoms in molecules (QTAIM) and noncovalent interactions (NCI) analysis. NCI analysis clearly shows that gases are captured by BP-TMACl complex through strong van der Waals forces. However, in capturing of SO2, strong electrostatic attractive forces are also involved. The nature of attractive forces is confirmed through QTAIM analysis. Furthermore, the relation between recovery time and desorption energy of captured gas molecules has been studied. The strongest absorption for SO2 results in prolonged recovery time for it (as compared to the other gas molecules). AIMD analysis is performed to find the dynamical stability of assembled-belts before and after loading ionic liquids along with gases to be captured. These results reveal that assembled-belts are suitable for encapsulation of ionic liquids along with capturing of gases. Overall, the best results are shown for SO2 capture. The study intends to deliver valuable information on the important progress in the environmental-remediation field and we hope our work is going to inspire more investigators to provide novel research on such challenging tasks.

Experimental and theoretical investigation of 1,3-bis(3-hydroxypyridinium)propane dibromide dihydrate, tetrabromozincate hydrate, and tetrabromocuprate

Three gemini hydroxypyridine salts: 1,3-bis(3-hydroxypyridinium)propane dibromide dihydrate (1), 1,3-bis(3-hydroxypyridinium)propane tetrabromozincate hydrate (2), and 1,3-bis(3-hydroxypyridinium)propane tetrabromocuprate (3) were synthesized and characterized by X-ray diffraction, FTIR, Raman, NMR, and DFT methods. The dibromide salt (1) crystallizes with two water molecules. One of the two bromide anions is connected to the hydroxyl group of one pyridinium cation moiety through the O(10)-H(10)···Br(2)− hydrogen bond of 3.146(2) Å, while the other bromide anion, Br(1)− is surrounded by three water molecules. In 1,3-bis(3-hydroxypyridinium)propane tetrabromozincate (2) the water molecule acts as a bridge between the hydroxypyridinium cation and the tetrabromozincate anion, while the tetrabromocuprate anion interacts directly with the hydroxypyridinium cation. The molecular structures of the studied 1,3-bis(3-hydroxypyridinium)propane derivatives 1a, 2a, and 3a were optimized using the APF-D/6–311++G(d,p) method. The optimized structure of salt 1a resembles the crystal structure, while in salts 2a and 3a the structure of 1,3-bis(3-hydroxypyridinium)propane dication is bent to the U-form and the tetrabromomethallate anion is located in a niche. The significant role of the intermolecular interactions and hydrogen bonds was revealed based on IR spectra. The interpretation of 1H and 13C NMR spectra in DMSO-d6 was based on 2D experiments. The quantum theory of atoms in molecules (QTAIM) was employed to classify the strength of hydrogen bonds in salts 1, 2, and 3. Based on the σ-hole concept, intermolecular interactions in 2 and 3 were described.

Ordering self-assembly structures via N[sbnd]H⋯S and Br⋯S interactions in (E)-2-(4-bromobenzylidene)hydrazinecarbothioamide : Insights from crystallographic and computational study

In this research paper, the compound (E)-2-(4-bromobenzylidene)hydrazinecarbothioamide (NC2) was synthesized and characterized by spectroscopic techniques and crystal structure was elucidated using single crystal X-ray diffraction method. The Hirshfeld surface analysis revealed the relative contributions of different intermolecular interactions to crystal packing, while the 2D fingerprint plots provided a visual representation of the intermolecular interactions via the surface area corresponding to each type of interaction. The findings revealed that the crystal packing of the molecule is mostly determined by H…H, C-Br…S and NH…S interactions. We investigated the structural and electronic properties of the compound NC2 using density functional theory (DFT). The optimized geometry, total energy, HOMO-LUMO gap, and vibrational spectra were calculated at the ωB97X/6–311+G(d,p) level of theory. The calculated results showed that the molecule has a stable geometry with a trans-conformation. The HOMO-LUMO gap of 3.813 eV indicates that the molecule has moderate stability. The nature of noncovalent interactions are investigated using the methods reduced density gradient (RDG) and topology analysis like quantum theory of atoms in molecules (QTAIM) proposed by Bader et al. The compound NC2 is found to adhere to the Lipinski's rule of five and exhibit good pharmacokinetic properties.

Supramolecular assembly in Cu(II) and Zn(II) compounds with pyridine and anthraquinone-1,5-disulfonate: Experimental and theoretical analysis

Two new multi-component coordination compounds of Cu(II) and Zn(II) viz. [Cu(py)2(H2O)4]ADS·2H2O (1) and [Zn(4-CNpy)2(H2O)4]ADS·2H2O (2) (py = pyridine, 4-CNpy = 4-cyanopyridine, ADS = anthraquinone-1,5-disulfonate) have been synthesized in aqueous media at room temperature and characterized using elemental and spectroscopic analyses (FT-IR, electronic), TGA and single crystal X-ray diffraction techniques. Both the compounds crystallize as metal–organic multi-component compounds containing complex cationic moieties along with uncoordinated anionic ADS moieties in the crystal structures. Crystal structure analysis of 1 reveals the stabilisation of the layered assembly of the compound assisted by CH⋯O, OH⋯O hydrogen bonding and π-stacking interactions. Antiparallel CN⋯CN and aromatic π-stacking interactions provide rigidity to the crystal structure of compound 2. In addition, enclathration of lattice water molecules within the supramolecular cavity of 2 provides additional reinforcement to the crystal structure. We have carried out theoretical investigations to analyze π-stacking, H-bonding and antiparallel CN···CN non-covalent interactions observed in the compounds using DFT calculations, quantum theory of atoms in molecules (QTAIM) and non-covalent interaction (NCI) plot index computational tools. The binding energies of the supramolecular assemblies are quite significant due to the ion-pair nature of the interactions which lack directionality; however, the aforementioned weaker non-covalent interactions play crucial roles in the final arrangement of molecules in the solid state due to their directional nature.

A combined experimental and theoretical approach for doxycycline sensing using simple fluorescent probe with distinct fluorescence change in wide range of interferences

Overuse of doxycycline (DOXY) can cause serious problems to human health, environment and food quality. So, it is essential to develop a new sensing methodology that is both sensitive and selective for the quantitative detection of DOXY. In our current research, we synthesized a simple fluorescent probe 4,4′-bis(benzyloxy)-1,1′-biphenyl (BBP) for the highly selective detection of doxycycline by through fluorescence spectroscopy. The probe BBP displayed ultra-sensitivity towards doxycycline due to Forster resonance energy transfer (FRET). Fluorescence spectroscopy, density functional theory (DFT), 1H NMR titration, UV–Vis, and Job's plot were used to confirm the sensing mechanism. The charge transfer between the probe and analyte was further examined qualitatively by electron density differences (EDD) and quantitively by natural bond orbital (NBO) analyses. Whereas the non-covalent nature of probe BBP towards DOXY was verified by theoretical non-covalent interaction (NCI) analysis as along with Bader's quantum theory of atoms in molecules (QTAIM) analysis. Furthermore, probe BBP was also practically employed for the detection of doxycycline in fish samples, pharmaceutical wastewater and blood samples.

Colorimetric detection of clotrimazole environmental pollutant using a newly developed chemosensor; an experimental and theoretical study

ABSTRACT Clotrimazole (CTZ), as an antifungal medication, is used to treat dermatological infections in humans, and to remove fungal infections from plants in agriculture, but its widespread usage has led to pharmaceutical pollution and environmental concerns. In this study, a new bromopyrogallol red (BPR) and N i 2 + based colorimetric sensor was developed for the selective and sensitive detection of CTZ. The BPR-Ni complex showed a clear colour change from purple to violet in the presence of CTZ, and a significant change was observed in the UV-Vis spectrum. The stoichiometric ratio of 1:1 between BPR and N i 2 + was determined using the Benesi-Hildebrand method. DFT and time-dependent DFT (TD-DFT) were applied to identify the molecular and electronic structures of the BPR, BPR-Ni, and BPR-Ni-CTZ in ground and excited states. The nature of electronic excitations and charge transfers was evaluated using the natural transition orbitals (NTO). The NTO analysis reveals that the Ni atom facilitates the charge transfer process between BPR and CTZ and improves the sensitivity of the chemosensor. The quantum theory of atoms in molecules (QTAIM) was employed to determine the nature of interactions between BPR, N i 2 + , and CTZ. This study paves the way for the detection of environmentally harmful pharmaceutical pollution using simple but effective colorimetric sensors.

An experimental and theoretical study on the molecular interactions of N-aromatic L-proline in the condensed phase

Intermolecular interactions, such as halogen bonding, π-π stacking, F…π interactions, and anion-π interactions, play pivotal roles in the fields of chemistry, materials science, and biological technology. In this study, N-aromatic L-proline and its fluorinated derivatives were chosen as exemplars. X-ray diffraction and NMR techniques were employed to investigate these interactions in both solid-state and solution phases respectively. Theoretical investigations encompassing geometry optimization along with QTAIM (Quantum Theory of Atoms in Molecule) and IGMH (Independent Gradient Model based on the Hirshfeld partition) analyses provided profound insights into the intermolecular interactions. Parameters obtained from X-ray diffraction analysis of single crystals provide compelling evidence for F…F interaction with intermolecular F…F distances measuring 2.879 Å and 3.125 Å in compounds 2 and 3 crystal structures respectively. QTAIM and IGMH analyses indicate that F…π contacts significantly contribute to the formation of these two fluorinated crystals while H-bonding and CH…π contacts predominantly shape the crystal structure of the non-fluorinated L-proline derivative.

Fascinating inclusion of metal–organic complex moieties in dinuclear Mn(II) and Zn(II) compounds involving pyridinedicarboxylates and phenanthroline: Experimental and theoretical studies

In the present study, we have reported the synthesis of two new dinuclear Mn(II) and Zn(II) metal–organic compounds, [Mn(2,5-PDC)(phen)2][Mn(phen)2(H2O)2]2Cl·10H2O (1) and [Zn(phen)3][Zn(2,6-PDC)2]·11.5H2O (2) (where, 2,5-PDC = 2,5-pyridinedicarboxylate, 2,6-PDC = 2,6-pyridinedicarboxylate, phen = 1,10-phenanthroline) at room temperature which have been characterized by elemental analysis, TGA, spectroscopic (FTIR, electronic) and single crystal X-ray diffraction techniques. A fascinating chloride-water supramolecular cluster in 1 and (H2O)13 H-bonded cluster in 2 along with π-stacked assemblies stabilize the solid state structures. The most interesting aspect of the crystal structure of 1 is the inclusion of complex cationic moieties within the infinite self-assembled chloride-water cluster. Similarly the inclusion of cationic complex moieties in compound 2 inside the supramolecular cavity formed by the anionic complex provides rigidity to the crystal structure. DFT calculations, molecular electrostatic potential (MEP) surface analysis, quantum theory of atoms-in-molecules (QTAIM) and the non-covalent index plot (NCI plot) analysis were performed to investigate the supramolecular assemblies of the compounds. The studies reveal that the antiparallel π-stacking interactions are energetically significant synthons for the assemblies. However, the assemblies in 2 have been dominated mostly by Columbic attraction of the cationic and anionic complex moieties.

Unraveling the crystal structure, stability and drug likeness of 1,3,4-oxadiazole derivatives against Myelofibrosis: a combined experimental and computational investigation

Herein, we report the synthesis and characterization of novel 1,3,4-oxadiazole derivatives, 2-methoxybenzyl 5-(4-chlorophenyl)-1,3,4-oxadiazole-2-carboxylate (C1) 2-methoxybenzyl 5-(2-chlorophenyl)-1,3,4-oxadiazole-2-carboxylate (C2), and methoxybenzyl 5-(3-chlorophenyl)-1,3,4-oxadiazole-2-carboxylate (C3) obtained through desulfurative cyclization reaction. The compound C2 was crystallized, and its crystal structure was elucidated using single-crystal X-ray diffraction technique. The Hirshfeld surface analysis was carried out to analyze, visualize and globally appreciate the weak interactions involved in crystal packing. These analyses were complemented by Quantum Theory of Atoms In Molecules (QTAIM) and Reduced Density Gradient (RDG), which allowed us to decipher the nature and types of attractive forces that contribute to maintain the crystal structure of the titled compound. Moreover, the ADME profile of the compound was predicted to assess its drug likeness. Finally, in silico studies were performed to explore the binding affinity of the compounds (C1–3) against Myelofibrosis through molecular docking and molecular dynamic simulations. Communicated by Ramaswamy H. Sarma

A theoretical study on 1H-indole-2,3-dione complexes with lithium, sodium, and potassium cations.

A comparative study of the change in different properties of electronic and structural of the free 1H-indole-2,3-dione molecule and its complexes has been obtained. HOMA analysis was performed to investigate the effects of lithium sodium and potassium cations on the aromaticity of lithium sodium and potassium complexes of 1H-indole-2,3-dione. Several 1H-indole-2,3-dione complexes with lithium, sodium, and potassium cations were optimized at the B3LYP/6-311G(d,p) level. The cation and π interaction has been investigated from different aspects, including interaction energy calculations, charge transfer values, and changes in the aromaticity of the ring upon complexation. The charge transfer and natural population analysis for the complexes were performed with the natural bond orbital (NBO) analysis. The properties of bond critical points in complexes were studied by applying the quantum theory of atoms in molecules (QTAIM). Finally, the aromaticity change of phenyl induced upon complex formation was evaluated by applying the harmonic oscillator model of aromaticity (HOMA). [Li-INa]+ and [[Li-INb]+ were optimized with the wB97XD function using a version of Grimme's D2 dispersion model, and the absorption energy was compared with the calculation made with the B3LYP functional.

On the Existence of Pnictogen Bonding Interactions in As(III) S-Adenosylmethionine Methyltransferase Enzymes.

As(III) S-adenosylmethionine methyltransferases, pivotal enzymes in arsenic metabolism, facilitate the methylation of arsenic up to three times. This process predominantly yields trivalent mono- and dimethylarsenite, with trimethylarsine forming in smaller amounts. While this enzyme acts as a detoxifier in microbial systems by altering As(III), in humans, it paradoxically generates more toxic and potentially carcinogenic methylated arsenic species. The strong affinity of As(III) for cysteine residues, forming As(III)-thiolate bonds, is exploited in medical treatments, notably in arsenic trioxide (Trisenox®), an FDA-approved drug for leukemia. The effectiveness of this drug is partly due to its interaction with cysteine residues, leading to the breakdown of key oncogenic fusion proteins. In this study, we extend the understanding of As(III)'s binding mechanisms, showing that, in addition to As(III)-S covalent bonds, noncovalent O⋅⋅⋅As pnictogen bonding plays a vital role. This interaction significantly contributes to the structural stability of the As(III) complexes. Our crystallographic analysis using the PDB database of As(III) S-adenosylmethionine methyltransferases, augmented by comprehensive theoretical studies including molecular electrostatic potential (MEP), quantum theory of atoms in molecules (QTAIM), and natural bond orbital (NBO) analysis, emphasizes the critical role of pnictogen bonding in these systems. We also undertake a detailed evaluation of the energy characteristics of these pnictogen bonds using various theoretical models. To our knowledge, this is the first time pnictogen bonds in As(III) derivatives have been reported in biological systems, marking a significant advancement in our understanding of arsenic's molecular interactions.

Bistriazolotriazole-tetramine: commendable energetic moiety and cation.

Various 7H,7'H-[6,6'-bi[1,2,4]triazolo[4,3-b][1,2,4]triazole]-3,3',7,7'-tetramine (A) based nitrogen-rich energetic salts were designed and their properties explored. All energetic salts possess relatively high nitrogen content (> 48%), positive heats of formation (> 429kJ/mol) and stability owing to a significant contribution from fused backbone. The cationic component shows a very high heat of formation (2516kJ/mol); therefore, it is highly suitable for enthalpy enhancement in new energetic salts. The cation was paired with the energetic anions nitrate (NO3-), perchlorate (ClO4-), dinitromethanide (CH(NO2)2-), trinitromethanide (C(NO2)3-), nitroamide (NHNO2-), and dinitroamide (N(NO2)2-) to improve oxygen balance and detonation performance. Designed salts show moderate detonation velocities (7.9-8.7 km/s) and pressures (23.8 - 33.1 GPa). The distribution of frontier molecular orbitals, molecular electrostatic surface potentials, QTAIM topological properties, and noncovalent interactions of designed salts were simulated to understand the electronic structures, charge distribution in molecules, hydrogen bonding, and other nonbond interactions. The predicted safety factor (SF) and impact sensitivity (H50) of designed salts suggest their insensitivity to mechanical stimuli. This work explored the 7H,7'H-[6,6'-bi[1,2,4]triazolo[4,3-b][1,2,4]triazole]-3,3',7,7'-tetramine as a suitable cationic component which could be promising and serve exemplarily in energetic materials. The optimization and energy calculations of all the designed compounds were carried out at the B3LYP/6-311 + + G(d,p) and M06-2X/def2-TZVPP levels, utilizing the Gaussian software package. The molecular surface electrostatic potential, quantum theory of atoms in molecules (QTAIM), reduced density gradient (RDG), and noncovalent interaction (NCI) analysis were performed by employing Multiwfn software. The EXPLO5 (v 7.01) thermochemical code and PILEM web application were used to predict the detonation properties.

A Charge-Charge Flux-Dipole Flux Analysis of Simple Molecular Systems with Halogen Bonds.

The presence of halogen bonds (R-X···B; R = substituent group, X = halogen, and B = Lewis base) provides quite amazing molecular systems for electronic structure investigations, presenting unique characteristics of fundamental relevance to supramolecular chemistry among other areas. Here, we use a double-hybrid approach from Density Functional Theory and triple-ζ basis sets augmented with diffuse functions (B2PLYP/def2-TZVPD) to deal with a large group of simple molecular systems containing halogen bonds (XBs), focusing on geometrical structures, binding energies, harmonic vibrational frequencies, and fundamental infrared intensities. Next, the electron densities and their variations on vibrations are carefully studied with the Quantum Theory of Atoms in Molecules (QTAIM) formalism and the charge-charge flux-dipole flux (CCFDF) model. We notice that the R-X stretching mode usually shows vibrational frequency decrements and infrared intensifications during the XB formation. Such features were also observed in hydrogen bonds, although the explanation for the band strengthening is different. Surprisingly, the most important contribution to these intensity increments due to complexation is now the interaction term between the charge flux and dipole flux (CF × DF). Thus, the use of atomic dipoles is mandatory to fully understand this phenomenon. In fact, the huge charge flux contributions to changes in dipole moment derivatives of R-X stretchings on halogen bonding are no longer accompanied by opposite variations of similar magnitudes in polarizations described by atomic dipole fluxes, which provided nearly unaltered values during the XB formation. Thus, the electronic charge flux direction change that takes place in complexes (from B to R) now reinforces dipole moment derivative terms from such atomic polarizations (mainly from the X atom). This intermolecular charge flux seems to be responsible for the unusual features noticed in the R-X stretching mode with the CCDDF/QTAIM model.

Theoretical Insights into Different Complexation Modes of Dioxovanadium(V) Compounds with Pyridoxal Semicarbazone/Thiosemicarbazone/S-Methyl-iso-thiosemicarbazone Ligands.

Vanadium complexes have gained considerable attention as biologically active compounds. In this contribution, three previously reported dioxovanadium(V) complexes with pyridoxal semicarbazone, thiosemicarbazone, and S-methyl-iso-thiosemicarbazone ligands are theoretically examined. The intermolecular stabilization interactions within crystallographic structures were investigated by Hirshfeld surface analysis. These experimental structures were optimized at the B3LYP-D3BJ/6-311++G(d,p)(H,C,N,O,S)/def2-TZVP(V) level of theory, and crystallographic and optimized bond lengths and angles were compared. High correlation coefficients and low mean absolute errors between these two data sets proved that the selected level of theory was appropriate for the description of the system. The changes in structures and stability were examined by adding explicit solvent molecules. The Quantum Theory of Atoms in Molecules (QTAIM) was employed to analyze the intramolecular interactions with special emphasis on the effect of substituents. A good correlation between electron density/Laplacian and interatomic distance was found. Through molecular docking simulations towards Bovine Serum Albumin (BSA), the binding affinity of complexes was further investigated. The spontaneity of binding in the active position of BSA was shown. Further experimental studies on this class of compounds are advised.

Cavitands based nanocapsule as smart and highly effective vehicle for 5-fluorouracil anti-cancer drug delivery: DFT insights

The nanomaterials have been widely investigated as drug delivery system for a variety of anticancer drugs to limit their adverse effects while transporting to the target site. In the current study, we report the cavitand-based nanocapsules as a drug delivery vehicle for nitrosourea (NU) and fluorouracil (FU) anti-cancer drugs. FU and NU drugs interact with the nanocapsules with the interaction energies in gas phase (solvent) −24.78 kcal/mol (–22.39 kcal/mol) and −21.58 kcal/mol (-20.45 kcal/mol), respectively. The results of Quantum theory of atoms in molecules (QTAIM) and noncovalent index (NCI) analyses indicate that the FU@Capsule and NU@Capsule complexes are mainly stabilized through hydrogen bonding and van der Waals interactions. Electron density difference (EDD) and natural bond order (NBO) analyses reveal that significant amount of charge is transferred from the nanocapsule to drug molecules. Frontier molecular orbital (FMO) analysis also reveals slight reduction in the energy gap. AIMDS analysis shows that cavitand capsules can efficiently carry the anti-cancerous drug to their target site without distorting complexes. The dipole moments and pH effect are studied to understand the drug release mechanism of considered anticancer drugs. The decrease in adsorption energy and increase in interaction distances indicate that anticancer drugs can easily be off-loaded from the carrier (nanocapsule) at the target site due to the low pH of cancerous cells compared to the normal cells. Therefore, cavitand nanocapsule can be employed as an excellent drug delivery carrier in smart targeted drug delivery.

On the role of water in antimony electrodeposition from choline chloride/ethylene glycol/water mixture

Through experimental research and theoretical calculation, it was investigated the effect of water and temperature on the electrodeposition of antimony (Sb) on a platinum (Pt) electrode. The plating solutions were prepared by the addition of 0.05 mol L–1 SbCl3 to the mixtures of choline chloride (ChCl), ethylene glycol (EG) and water (W) in the following molar ratio: 1ChCl:2EG (bath 1), 1ChCl:2EG:0.45 W (bath 2), and 1ChCl:2EG:1.62 W (bath 3). Furthermore, the Sb coatings were electrodeposited at 297 and 338 K. The surface morphologies and crystalline structures of Sb electrodeposits were analysed by scanning electron microscopy (SEM) and X-ray diffraction (XRD), respectively. In addition, to understand the interactions of Sb3+ species with the other components of the plating solution, models were created and calculated using density functional theory (DFT) and quantum theory of atoms in molecules (QTAIM). The results of the voltammetric behaviour of Sb3+ species indicated that the reduction potential was shifted towards more positive values with increasing water content on the electrolyte, indicating that the water catalyses the electrochemical reduction of the Sb3+ species. The values of the diffusion coefficients for the Sb3+ species were calculated by applying the Cottrell equation, which increased with the addition of water and temperature increment. The water content and temperature increase affect the surface morphologies of the Sb electrodeposited coatings, which is attributed to the improvement of Sb electrodeposition rate. Moreover, Sb electrodeposited coatings were successfully obtained without adding a complexing agent, indicating that the procedure adopted for the Sb electrodeposition is environmentally friendly. The XRD results revealed the pure phase Sb films. DFT simulations indicated that the Sb-Cl interaction is stronger, which suggests the formation of Sb-Cl complexes. Adding H2O molecules favours the electron affinity of the systems, and QTAIM results suggested that this additive decreased the electron density of Sb3+ ions.

Extensive optical and DFT studies on novel AIE active fluorescent sensor for Colorimetric and fluorometric detection of nitrobenzene in Solid, solution and vapor phase

An electron rich isophthalamide based sensor IPA has been synthesized through a simple two-step reaction, containing noteworthy aggregation induced emission (AIE) properties. Considering the significant emission with λmax at 438 nm, sensor IPA has been employed for the sensing of nitrobenzene (NB) in solid, solution and vapor state with high sensitivity and selectivity. Sensor IPA showed noteworthy colorimetric and fluorometric quenching in fluorescence emission when exposed to NB. Small size of NB and involvement of photoinduced electron transfer (PET) lead to detection of NB down to 60 nM. IPA-NB interaction was studied through UV–Vis. spectroscopic studies along with fluorescence spectroscopy. Moreover, 1H and 13C NMR titration experiments provided additional support for determination of interaction type. Furthermore, by using density functional theory (DFT) calculations, thermodynamic stability was studied. Additionally, non-covalent interactions (NCI), frontier molecular orbitals (FMO), density of states (DOS), were investigated for providing further evidence of nitrobenzene sensing and its interaction with sensor. Natural bond orbital (NBO) analysis was carried out for charge transfer studies. Quantum theory of atom in molecule (QTAIM) and SAPT0 studies provided information about interaction points and binding energy. Additionally, IPA was investigated for NB sensing in real water samples, and its effective participation in solid state on-site detection as well as in solution phase was brought to light along with logic gate construction.

Investigating structural dynamics and sensing capabilities: Spectroscopic and DFT analysis of novel AIEE active deferasirox based organic sensor

A deferasirox based sensor DPA was rationally designed through single step amidation reaction. Sensor DPA exhibited aggregation induced emission enhancement (AIEE) property that was attributed to restriction in intramolecular rotation (RIR). Moreover, the sensor DPA displayed remarkable bathochromic shift (red-shift) of 110 nm in wavelength, ascribed to formation of J-aggregates. Furthermore, sensor DPA was employed for the selective and sensitive fluorescence based sensing of hazardous and carcinogenic nitrobenzene (NB). The sensor DPA successfully detected NB in solution through the quenching of emission intensity. The quenching of sensor fluorescence intensity was ascribed to photoinduced electron transfer (PET) mechanism. The sensing mechanism was investigated by 1H NMR titration experiment, Job's plot and density functional theory (DFT) calculations. Additionally, the existence of non-covalent interactions between sensor DPA and NB were examined by Bader's Quantum theory of atoms in molecules (QTAIM) and non-covalent interaction (NCI) analysis. Finally, sensor DPA was employed for the detection of volatile nitrobenzene in vapor phase.

Quantitative clustering and matching of conformers using average electron densities

This study presents a new approach of quantitatively clustering conformers of small molecules, such that conformers of the same group share similar electrostatic potential (ESP) maps. This helps expedite the drug design process as ESP maps guide the “key & lock” complementarity between a molecule and its receptor. The clustering is based on similarities in the average electron density (AED) of a group of interest within a molecule. AED values are computationally evaluated using the quantum theory of atoms in molecules (QTAIM). The AED tool was validated, separately, on 43 conformers of ibuprofen and 40 conformers of a tetrazole analogue of ibuprofen. The conformers were grouped based on their AED values using the K-means clustering method. It was found that conformers of the same group share similar ESP maps, with a remarkable accuracy exceeding 96%. In addition, using a drug design concept known as bioisosterism, it was found that the AED tool depicts similarities in the ESP maps of not only conformers of a single molecule, but also conformers of different molecules that share similar biological activities.

Theoretical Study of Am(III) and Eu(III) Separation by a Bipyridyl Phosphate Ligand.

Actinide An(III) and lanthanide Ln(III) are known to exhibit similar chemical properties; thus, it is difficult to distinguish them in the separation of highly radioactive waste liquids. One potential method to efficiently separate actinides and lanthanides involves the design and development of phosphorus-oxygen-bonded ligands with solvent extraction separation. Here, a bipyridine phosphate ligand with two isopropyl and phosphate groups is introduced to selectively extract actinides. The electronic structure, bonding properties, thermodynamic behavior, and quantum theory of atoms in molecules (QTAIM) of Am(III) and Eu(III) complexes with the bipyridine phosphate ligands were analyzed by using density functional theory (DFT) calculations. The analysis demonstrates that the Am-N bond exhibits stronger covalent characteristics than the Eu-N bond, indicating that the bipyridine phosphate ligand had better selectivity for Am(III) than for Eu(III) in terms of binding affinity. The thermodynamic analysis established the complex [ML(NO3)2(H2O)2]+ as the most stable species during the complexation process. The results indicate great potential for utilizing the bipyridine phosphate ligand for the effective separation of An(III)/Ln(III) in spent fuel reprocessing experiments.