NCI Plot Research Articles

Dynamics of the interaction between water and the amino acids alanine, arginine, asparagine and glutamine using LED, QTAIM, AIMD and core-valence bifurcation (CVB) index

The interplay of solvents is important in biological systems. This study examines the interaction between the water molecule and the amino acids viz, alanine, arginine, asparagine, and glutamine. The primary cause of the interaction is the hydrogen bond that forms between the oxygen atom in the water molecule and the hydrogen of the amino acid’s –OH group of the –COOH. The DFT approach was used to analyse the non-covalent interaction in gas phase. The NBO analysis is used to investigate the electron delocalisation between the amino acid and the water molecule. Binding energy is calculated using the QTAIM analysis and found that the asparagine – water system has more binding energy compared to the other four amino acid under consideration. RDG plots and NCI plots were used to analyse the non-covalent interaction between the moieties. DLPNO-CCSD(T) energy is decomposed into various components using the local energy decomposition method and the binding strength is analysed. AIMD analysis further confirms the stability of the interaction of water at the –COOH group of the amino acid. The hydrogen bonding strength is determined from the CVB index and the strong hydrogen bonding among the four amino acid is found in the asparagine – water system.

Synthesis and X-ray characterization of two new 1,4-benzoxazine derivatives: Structural analysis and DFT calculations

The synthesis and XRD characterization of two new 1,4-benzoxazine derivatives (3a-5a) namely ethyl‐6‐nitro‐3a‐(p‐tolylamino)‐1,2,3,3a‐tetrahydrobenzo[b]cyclopenta[e][1,4]oxa-zine‐9a(9H)‐carboxylate (3a) and methyl-6,10b-dimethyl-5a,6,10b,11-tetrahydrobenzo[5,6][1,4]oxazino[2,3-b]indole-2-carboxylate (5a) are reported herein. In both compounds it is observed the formation of π···π and CH···π interactions and strong NH···O H-bonds, which were studied energetically at the PBE0-D3/def2-TZVP level of theory. The Hisrhfeld surface and QTAIM analyses and NCI plots were used to study the nature and the extent of different intermolecular interactions observed in both structures, revealing the existence of additional R21(6) and R21(7) synthons. In addition, using the potential energy density as energy predictor, the QTAIM method is useful to investigate the relative contribution of each interaction to the formation of the assemblies.

Supramolecular assemblies involving unusual N(nitrile)∙∙∙π(fum) and nitrile-nitrile non-covalent contacts in fumarato and succinato bridged polymers of Co(II) and Ni(II): Experimental and theoretical studies

Two new Co(II) and Ni(II) coordination polymers viz. [Co(H2O)2(μ-fum)(3-CNpy)2]n (1) and {[Ni(H2O)2(μ-succ)(4-CNpy)2]·2H2O}n (2) (where, fum= fumarate, CNpy = cyanopyridine, succ = succinate) have been synthesized and characterized using single crystal XRD, elemental analysis, spectroscopic (IR and electronic) techniques and TGA. Compound 1 crystallizes as a fumarato bridged Co(II) polymer; whereas, compound 2 is a succinato bridged Ni(II) polymer. The presence of various non-covalent interactions in the compounds stabilizes the layered assemblies of the compounds. Antiparallel nitrile∙∙∙nitrile interactions are observed in both the crystal structures involving the nitrile moieties of coordinated CNpy which provide rigidity to the compounds. Further analysis reveals that the N-atom of –CN group of 3-CNpy in 1 is involved in unusual N(nitrile)∙∙∙π(fum) interactions with the π-electrons of the C=C bond of fum. Enclathrated (H2O)2 cores within the supramolecular host cavity of compound 2 provides additional reinforcement to the crystal structure. We have also carried out theoretical studies to analyze the π-stacking and H-bonding interactions present in the crystal structure of compound 1 using quantum theory of atoms-in-molecules (QTAIM), non-covalent interaction plot (NCI plot) and molecular electrostatic potential (MEP) surface analysis. The MEP value at the N-atom of the cyano group of 1 is negative and the value is neutral over the double bond of the fum; indicating the possibilities of formation of N(nitrile)∙∙∙π(fum) interactions. Energetic analysis suggests that antiparallel π-stacking observed between the 3-CNpy moieties in 1 is the most dominating force followed by N(nitrile)∙∙∙π(fum) interaction and finally the H-bonds.

An insight into the non-covalent Cl•••Cl interaction in the solid state structure of carboxylate bridged trinuclear mixed valence cobalt(III/II/III) complexes with tetradentate N2O2 donor reduced Schiff base ligands

Two mixed-valence trinuclear cobalt(III)-cobalt(II)-cobalt(III) complexes, [CoII{(μ-L1)(μ-OOCC6H5NO2)CoIII(N3)}2] (1) and [CoII{(μ-L2)(μ-OOCC6H4NO2CH3)CoIII(N3}2] (2) have been synthesized using two tetradentate N2O2 donor 'reduced Schiff base' ligands, H2L1 {2,2-dimethyl-1,3-propanediyl)bis(iminomethylene)bis(4-chlorophenol}, and H2L2{2-hydroxy-1,3-propanediyl)bis(iminomethylene)bis(4-chlorophenol}, and 3-nitrobenzoic benzoic acid or 4-methyl 3-nitrobenzoic benzoic acid as anionic co-ligands. The complexes have been characterized by spectroscopic measurements and their solid state structures have been determined by single crystal X-ray diffraction analysis. The trinuclear cobalt(III)-cobalt(II)-cobalt(III) skeleton of both the complexes are linear and centrosymmetric. Both the central cobalt(II) and terminal cobalt(III) of both the complexes are hexa-coordinated. DFT calculations have been used to analysed some supramolecular assemblies of the complex that have been observed in the solid state, specifically the Cl···Cl interactions that result in the creation of a stable 2D supramolecular assembly in the solid state. QTAIM and NCI Plot computational tools have been used to characterize the interactions. Thermo-gravimetric (TG) analysis was used to examine the thermal behaviour of both complexes. The redox behaviors of both the complexes were studied by using Cyclic Voltammetry (CV).

Investigating the potential of carbon nitride as a new sensing material for NOx (N2O, N2O3, N2O4, and N2O5): a DFT study

Herein, DFT study was used to investigate the carbon nitride C6N8 as a potential detector of noxious gases, specifically nitrous oxide (N2O), dinitrogen tri-oxide (N2O3), dinitrogen tetra-oxide (N2O4), and dinitrogen penta-oxide. (N2O5). The Physiosorption process was notified after the adsorption of N2O (−12.6463 kJ mol–1), N2O3 (−40.1466 kJ mol–1), N2O4 (−23.8512 kJ mol–1), and N2O5 (−29.7947 kJ mol−1) on C6N8. The adsorption behavior shows weak interactions in the complexes which depicts the stability trend as N2O3@C6N8 > N2O5@C6N8 > N2O4@C6N8 > N2O@C6N8. Various analyses and techniques were employed to evaluate the sensing capability. Electronic parameters such as FMO, ELF, NBO, UV-visible spectrum, and DOS were performed to notify the detectable change in the sensing surface after the adsorption of the gases being studied. The existence of non-covalent interactions was confirmed by Symmetry Adopted Perturbation Theory (SAPT0), QTAIM, NCI, and IRI plots. Moreover, SAPT0 confirmed the greater contribution of Edispersion in N2O@C6N8. ESP (MEPs) visualization confirmed the interactions, as the nitrogen atoms of the surface are electron dense regions for the analytes to attack. Chemical stability and selectivity were evidenced by the stability parameters and the formation of new states in the DOS spectrum, respectively. Significant recovery time performance was observed after evaluating the recovery of analyte@C6N8 complexes at an appropriate temperature. These results suggest C6N8 theoretically as a potentially active sensing surface and it will enhance the interest of the experimental researchers in fabricating a sensing device using this material for the determination of even minute concentrations of the toxic gases.

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.

Synergistic charge-transfer dynamics of novel pyridoquinazolindone-containing triphenylamine-based push-pull chromophores: from structural optimization to performance metrics in photovoltaic solar cells and static, dynamic, solvent-dependent nonlinear optical response applications.

Modern technological breakthroughs depend on nonlinear optical (NLO) and photovoltaic (PV) materials, essential for creating advanced photonic devices and efficient solar cells. Herein, the NLO, PV, electrical, and photophysical characteristics of proposed chromophores (WLK-1-WLK-6) designed from pyridoquinazolindone-containing triphenylamine have been systematically altered by the addition of different spacers categorized as K1, K2, K3, K4, K5, and K6 (named as i-series). This fine-tuning was accomplished using TD-DFT, DFT computations, and the Scharber model. The impact of spectrum of medium polarity, ranging from the least polar to the most polar, including water (ε = 78.36), methanol (ε = 32.61), DMSO (ε = 46.83), tetrahydrofuran (ε = 7.43), benzene (ε = 2.27) and chloroform (ε = 4.71), is explored in detail utilizing the IEFPCM model on NLO and PV properties. Moreover, the response of different analyses like DOS, NCI, NBO, FMO, dipole moments (µ), and hyperpolarizability (β) in both gas, polar and non-polar solvents was analyzed. Our structure-property relationship studies revealed that adding extra spacer groups, particularly those containing thiophene spacers, considerably impacted the lowering of the energy gap (3.853-4.190 eV). The simulated UV-Vis spectra illustrate significant π → π* transitions and lower n → π* transitions, primarily in the near-infrared (IR) range of 558.613 to 429.844 nm. Push-pull chromophores showed extraordinary frequency-dependent NLO properties, SHG β(-2ω, ω, ω), and EOPE β(-ω, ω, 0) effect computed at laser frequencies of 1064 and 532 nm. Among the proposed compounds, WLK-6 with the K6 spacer demonstrated a smaller energy gap (3.853 eV), resulting in a maximum optical absorption peak at λ max = 558.613 nm and the maximum hyperpolarizability in benzene (9.00 × 104 a.u.), methanol (1.22 × 105 a.u.), THF (1.12 × 105 a.u.), DMSO (1.23 × 105 a.u.), and water (1.23 × 105 a.u.). Our study found that WLK-6, WLK-5, and WLK-1 compounds also had good photovoltaic (PV) capabilities, reaching a power conversion efficiency (PCE) of around 5% and an injection efficiency (ΔG inject) of 0.191. In addition to these analyses, we performed topologic studies, such as TDM, ELF, NCI, MEP, LOL, and electron-hole overlap plots to better understand both intra and intermolecular interactions. Based on these results, it is clear that modifying longer π-linker groups in A-D-π-A conjugated systems benefits the optoelectronic characteristics and NLO responses for organic PV devices.

Graphene oxide incorporated PSU/SPEKEKK for potential application as proton exchange membranes in fuel cells

This study aims to develop a new PEM for fuel cell applications consisting of PSU/SPEKEKK/SGO membranes with improved physiochemical properties to surmount the low power generation of Nafion. The DFT calculations using NCI plots show that there are network interactions between PSU and SPEKEKK, established by the hydrogen bonding and vdW interactions. SGO was incorporated into the as-prepared PSU/SPEKEKK membrane. A solution casting method was employed to fabricate SGO-loaded composite membranes in the range of 0.1% to 1.5% (wt%). Structural evidence of the SGO and composite membranes was characterized by ATR-FTIR and FESEM, respectively. Adding SGO to PSU/SPEKEKK shows a significant increase in proton conductivity due to the presence of more protonated sites (SO3H) and water-mediated interactions for proton conduction. Of all the compositions considered, PSU/SPEKEKK/SGO-0.6-1.5% loading was found to have the highest proton conductivity, 0.03Scm−1. Although adding SGO to the composite membrane has reduced water absorption, the hydrophilic oxygenated functional groups in SGO, the bound water molecules, and the increased –SO3H groups have successfully improved the proton conductivity. The findings reveal that all composite membranes show excellent oxidative stabilities for 32 h in Fenton's reagent. To summarize, all composite membranes fabricated in this study show acceptable water uptake and swelling ratio, high oxidation, excellent thermal stability, and high proton conductivity.

Crystallographic, theoretical and conductivity studies of two new complexes [Ni(II) and Cu(II)] based on mixed ligands approach

Two new complexes [Ni(C7H3NO5) (C15H11N3)]. 4(H2O) (1) and [Cu(C7H3NO5) (C15H11N3)]. 4(H2O) (2) have been synthesized using mixed chelating ligands [4-hydroxypyridine-2,6-dicarboxylic acid (chelidamic acid) (C7H5NO5) and 2,2′:6′,2′′-terpyridine (C15H11N3)] in aqueous medium. The two complexes were characterized by UV–visible, IR spectroscopy as well as by single-crystal X-ray diffraction analysis. The geometries of both the complexes are distorted octahedral with N4O2 chromophore. The non-covalent interactions found in the solid state architectures of complexes 1 and 2 have been described focusing on π•••π stacking and hydrogen bonding interactions. These non-covalent interactions played an imperative role in building of multi-dimensional supramolecular architectures. These interactions have been explored theoretically by density functional theory (DFT) focusing on the antiparallel π-π stacking in self-assembled dimers and the hydrogen bonding networks mediated by the lattice water molecules. MEP surface calculations combined with QTAIM and NCI plot analysis were used to rationalize and characterize the non covalent interactions involved in the assemblies. The low optical band gaps of the two complexes exhibit semiconducting property leading to potentially fabricate Schottky Barrier Diode.

Identification of anti-cancer organometallic compounds by inhibition of BCL-2/Bax interactions

Apoptosis is regulated by the BCL-2 family, which includes the anti-apoptotic and pro-apoptotic proteins (Bax, Bok, Bak, etc.). These proteins often interact in dimers and act as apoptotic switches. Anti-apoptotic proteins, such as BCL-2, block the functions of these pro-apoptotic proteins. The pro-apoptotic and anti-apoptotic protein-protein interactions must be inhibited to prevent tumor cells from escaping apoptosis. This method has been used to develop anticancer drugs by inhibiting BCL-2 with both natural and synthetic compounds. Metal-containing compounds were used as pharmaceuticals for human cancer patients for a long time, and cisplatin was the first candidate of this class. Drug design, however, needs to pay more attention to metal complexes. We have studied the X-ray crystal structure of the BCL-2 protein in detail and identified the hydrophobic nature of the site with two less solvent-accessible sites. Based on the hydrophobic nature of the compounds, 74 organometallic compounds with X-ray crystallographically characterized bioactivity (including anticancer activity) were selected from the Cambridge crystallographic database. For testing, molecular docking was used to determine which compound was most effective against the BCL-2 protein. Organometallic compounds (benzene)-chloro-(1-{[(9H-fluoren-2-yl)imino]methyl}naphthalen-2-olato)-ruthenium (2), (1-((1,1′-biphenyl)-4-yl)-2,3,4,5-tetramethylcyclopentadienyl)-chloro-(4,4′-dimethyl-2,2′-bipyridine)-rhodium hexafluorophosphate (37), (μ-1,1'-(butane-1,4-diyl)bis(3-oxy-2-methylpyridin-4(1H)-one))-dichloro-bis(pentamethyl-cyclopentadienyl)-di-rhodium tetrahydrate (46), (μ-1,1'-(butane-1,4-diyl)bis(3-oxy-2-methylpyridin-4(1H)-one))-dichloro-bis(pentamethyl-cyclopentadienyl)-di-iridium (47) etc are found to be important compounds in this study. The capability of different types of complex interactions was identified using Hirshfeld surface analysis of the complexes. A NCI plot was conducted to understand the nature of the interaction between complex amino acids and active-site amino acids. A DFT study was conducted to examine the stability and chemical reactivity of the selected complexes. Using this study, one suitable hydrophobic lead anti-cancer organometallic pharmaceutical was found that binds at the less solvent-accessible hydrophobic site of BCL-2.

Structural and computational insights into two trimethylenedipyridine co-crystals: Inputs from X-ray diffraction, Hirshfeld surface, PIXEL, QTAIM and NCI plots

Two trimethylenedipyridine co-crystals, [(TMDP)·(H2OBA)] (1) and [(TMDP)·(SUC)] (2) [TMDP = 4, 4′-trimethylenedipyridine, H2OBA = 4,4′-oxybis(benzoic acid), and SUC = succinic acid) were designed, synthesized and their single crystals were grown by slow evaporation technique. The grown crystals were characterized by elemental analysis and UV–Vis spectroscopic technique, and the structures of the grown crystals were elucidated using single-crystal X-ray diffraction analysis. Supramolecular assemblies of co-crystal (1) are stabilized through several intermolecular hydrogen bonds such as O‒H···N, C‒H···O, C‒H···π, as well as π···π interactions whereas for co-crystal (2) only intramolecular hydrogen bonding interaction, O‒H···N is responsible for stabilization of supramolecular network. Hirshfeld surfaces were used to gain additional insight into non-covalent interactions in molecular crystals, and 2D fingerprint plots provided a quantitative analysis of different non-covalent interactions in the crystal structures. The interaction energies of the molecular pairs, as well as the lattice energies of the crystal structures, have been studied using the PIXEL method. The nature and strength of the non-covalent interactions at their (3, –1) bond critical points (BCPs) have been explored using Bader's quantum theory of “Atoms in Molecules” (QTAIM). The non-covalent interactions were further characterized through the NCI plots.

Self-assembly, crystal structure, computational studies, optical investigation, magnetic and biological properties of novel compounds based on methoxyphenyl piperazinium ligand

Two novel methoxyphenyl-based piperazine compounds have been investigated. The crystal structures of [C11H18N2O][Co(SCN)4] (1) and [(C11H18N2O)4]Cl8.7H2O (2) have been determined using single crystal X-ray crystallography. However, (1) crystallizes in an orthorhombic system with the non-centrosymmetric space group P 212121 with the following lattice parameters: a=8.4637(2) Å, b=14.5848 (5) Å, c= 17.1847 (5) Å with V =2121.3 (1) Å3 and Z = 4, otherwise (2) crystallizes in monoclinic system with P 21/c space group and the following lattice parameters: a=7.2551 (2) Å, b=9.0523 (4) Å, c= 22.3575 (8) Å, β = 95.998 (3)° with V =1460.30 (9) Å3 and Z = 1 . Different interactions packed the system through N-H…S hydrogen bonds for (1). The organic entities are grouped into dimers for (2) through weak interactions and N-H∙∙∙Cl, N-H∙∙∙O, and O-H∙∙∙Cl. The robustness of the crystals is also enhanced by C–H…π of the piperazine ring. Infrared spectrums were recorded to reveal the vibrational modes of the compounds, and to highlight the optical behavior, UV–visible analysis has been carried out. Thermal analysis was carried out to highlight the thermal stability of complexes. In addition, the antibacterial assets were investigated against different bacteria. The 13C Nuclear Magnetic Resonance was carried out to highlight the presence of primary reagents in the final product. Intermolecular interaction and stabilization of dimer complexes in the crystal packing are explored using Hirshfeld surface analysis to highlight the role of molecular interaction in the crystal packing. The more detailed quantum computation from crystallographic reported self-assembled dimer complexes occurred for comprehensive structure elucidation and showed good findings. The nature of dimer complexes has been assessed by strong and weak intermolecular interactions which were examined by NCI plots and analyzed by QTAIM calculation. Then, the thermal analysis was used to confirm the crystal thermal stability, Furthermore, biological behavior was performed for the compounds against different antibacterial targets to identify to which target the compounds show the best affinity. and finally, the magnetic properties were studied to show the spin coupling for the metal complex. Magnetic measurements of the novel cobalt compound show χT values that are typical for Co(II) cations with S = 3/2.

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.

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.

Insights into Synthesis, Crystal Structure, Bioactivity and Computational Studies of Cu(II) and Zn(II) Carboxylates Containing Aminopyridine

Abstract[Cu2(μ‐2‐chlorobenzoato‐O,O’)4Cl2].2(4‐DMAPH) (1) and [Zn2(μ‐2‐chlorobenzoato‐O,O’)4(4‐DMAP)2] (2) (4‐DMAP=4‐Dimethylaminopyridine) were synthesized from CuCl2/Zn(NO)3)2 . 6H2O, 2‐chlorobenzoic acid and 4‐dimethylaminopyridine in methanol under reflux. Compounds were comprehensively characterized by elemental analyses, conductance measurement, spectroscopic and X‐ray diffraction studies. Complexes crystallized in the monoclinic space group P21/n having dinuclear paddle‐wheel structure. DFT studies along with NCI plot, QTAIM analysis indicate presence of N−H⋯Cl, C−H⋯O, C−H⋯π interactions in 1 and CH3⋯π, π⋯π and C−H⋯Cl in 2. The charge distribution in the complexes was shown via MEP analysis. Complexes interact with CT‐DNA in moderately strong non‐intercalative mode of binding. Antimicrobial study against Shigella flexneri (B), Streptococcus pneumoniae (K), Klebsiella pneumoniae (P) and Shigella boydii (Q) shows appreciable activity of 1 whereas compound 2 is comparatively less active. In vitro cytotoxicity study against cell lines (L‐132) exhibits moderate activity by the complexes, but compound 2 shows significant cell inhibition activity against cell lines K‐562. The complexes are emissive in nature.

Cyclotetrabenzil Derivatives for Electrochemical Lithium‐Ion Storage

AbstractOrganic electrode materials could revolutionize batteries because of their high energy densities, the use of Earth‐abundant elements, and structural diversity which allows fine‐tuning of electrochemical properties. However, small organic molecules and intermediates formed during their redox cycling in lithium‐ion batteries (LIBs) have high solubility in organic electrolytes, leading to rapid decay of cycling performance. We report the use of three cyclotetrabenzil octaketone macrocycles as cathode materials for LIBs. The rigid and insoluble naphthalene‐based cyclotetrabenzil reversibly accepts eight electrons in a two‐step process with a specific capacity of 279 mAh g−1 and a stable cycling performance with ≈65 % capacity retention after 135 cycles. DFT calculations indicate that its reduction increases both ring strain and ring rigidity, as demonstrated by computed high distortion energies, repulsive regions in NCI plots, and close [C⋅⋅⋅C] contacts between the naphthalenes. This work highlights the importance of shape‐persistency and ring strain in the design of redox‐active macrocycles that maintain very low solubility in various redox states.

Cyclotetrabenzil Derivatives for Electrochemical Lithium-Ion Storage.

Organic electrode materials could revolutionize batteries because of their high energy densities, the use of Earth-abundant elements, and structural diversity which allows fine-tuning of electrochemical properties. However, small organic molecules and intermediates formed during their redox cycling in lithium-ion batteries (LIBs) have high solubility in organic electrolytes, leading to rapid decay of cycling performance. We report the use of three cyclotetrabenzil octaketone macrocycles as cathode materials for LIBs. The rigid and insoluble naphthalene-based cyclotetrabenzil reversibly accepts eight electrons in a two-step process with a specific capacity of 279 mAh g-1 and a stable cycling performance with ≈65 % capacity retention after 135 cycles. DFT calculations indicate that its reduction increases both ring strain and ring rigidity, as demonstrated by computed high distortion energies, repulsive regions in NCI plots, and close [C⋅⋅⋅C] contacts between the naphthalenes. This work highlights the importance of shape-persistency and ring strain in the design of redox-active macrocycles that maintain very low solubility in various redox states.

Substituent Effects in Tetrel Bonds Involving Aromatic Silane Derivatives: An ab initio Study.

In this manuscript substituent effects in several silicon tetrel bonding (TtB) complexes were investigated at the RI-MP2/def2-TZVP level of theory. Particularly, we have analysed how the interaction energy is influenced by the electronic nature of the substituent in both donor and acceptor moieties. To achieve that, several tetrafluorophenyl silane derivatives have been substituted at the meta and para positions by several electron donating and electron withdrawing groups (EDG and EWG, respectively), such as -NH2, -OCH3, -CH3, -H, -CF3 and -CN substituents. As electron donor molecules, we have used a series of hydrogen cyanide derivatives using the same EDGs and EWGs. We have obtained the Hammett's plots for different combinations of donors and acceptors and in all cases we have obtained good regression plots (interaction energies vs. Hammet's σ parameter). In addition, we have used the electrostatic potential (ESP) surface analysis as well as the Bader's theory of atoms in molecules (AIM) and noncovalent interaction plot (NCI plot) techniques to further characterize the TtBs studied herein. Finally, a Cambridge Structural Database (CSD) inspection was carried out, retrieving several structures where halogenated aromatic silanes participate in tetrel bonding interactions, being an additional stabilization force of their supramolecular architectures.

Unconventional Dual Donor-Acceptor Topologies of Aromatic Rings in Amine-Based Polymeric Tetrahedral Zn(II) Compounds Involving Unusual Non-Covalent Contacts: Antiproliferative Evaluation and Theoretical Studies

Two Zn(II) coordination polymers, viz., [Zn2Cl2(H2O)2(µ-4-AmBz)2]n (1) and [ZnCl2(µ-3-AmPy)2]n (2) (4-AmBz = 4-aminobenzoate, 3-AmPy = 3-aminopyridine) have been prepared at room temperature and characterized using elemental analysis, FT-IR, electronic spectroscopy, TGA (thermogravimetric analysis) and single crystal XRD. Crystal structure analyses of the polymers unfold the presence of non-covalent anion–π, π-stacking and unusual NH2(amino)⋯π interactions which provide rigidity to the crystal structures. Unconventional Type I Cl⋯Cl interactions also play a pivotal role in the stability of compound 1. Molecular electrostatic potential (MEP) surface analysis reveals that the MEP values over the center of the aromatic rings of coordinated 4-AmBz and 3-AmPy moieties are positive on one side and negative on the other side which confirms the dual non-covalent donor-acceptor topologies of the aromatic rings and explains the concurrent formation of unusual non-covalent NH2···π and anion–π interactions. DFT (density functional theory) calculations, QTAIM (quantum theory of atoms in molecules) and NCI plot (non-covalent index) index analyses reveal that among various non-covalent contacts involved in the crystal packing of the compounds, H-bonds in compound 1 and π-interactions (NH2···π, π-π, anion–π) in compound 2 are energetically significant. We have explored in vitro cytotoxic potential of the compounds in Dalton’s lymphoma (DL) cancer cells using trypan blue and apoptosis assays. The studies show that compounds 1 and 2 can significantly exhibit cytotoxicity in DL cells with minimum cytotoxicity in healthy PBMC cells. Molecular docking studies reveal that the compounds effectively bind with the antiapoptotic target proteins; thereby establishing a structure activity relationship of the compounds.

Combined experimental and theoretical studies of bis-chalcone: Estimation of non-covalent interactions

A new bischalcone BCH (2E,2′E)-1,1′-(((1,4-phenylenebis(methylene))bis(oxy))bis(2,1-phenylene))bis(3-(4-(benzyloxy)phenyl)prop‑2-en-1-one) has been synthesized and characterized by spectroscopic and single crystal X-ray diffraction techniques. The C–H···O and C–H···π intermolecular non-covalent interactions play crucial contribution in the formation of supramolecular architecture. A comprehensive Hirshfeld surface analysis and 2D fingerprint plots reveal the presence of intermolecular non-covalent interactions and percentage contributions of individual atoms. Hirshfeld energy framework calculations demonstrate dominance of dispersion energy. DFT calculations have been carried out energetic evaluation of non-covalent interactions. The charge distribution is rationalized by MEP surfaces. NCI Plot and QTAIM analysis have been computed to quantification of non-covalent interactions in the stabilization of the molecular crystal packing.