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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. [ABSTRACT FROM AUTHOR]

This manuscript reports a synthetic protocol to obtain 3-substituted 4,5-dichloroisothiazole derivatives in good yields. This is exemplified by the synthesis of six new compounds, which have been spectroscopically characterized including their solid state structure by single crystal X-ray analysis. As substituents in position 3, both 1,4-dihydropyridinyl and 4H-pyranyl moieties have been used, decorated with several groups like cyano, amino, acetyl, ester and methyl, thus providing a variety of possibilities to establish noncovalent interactions. The assemblies have been analysed theoretically, using DFT calculations, molecular electrostatic potential (MEP) surfaces and QTAIM/NCIplot calculations. The π-stacking between the 4,5-dichloroisothiazole rings is a recurrent motif in the solid state of most compounds, in addition to other less conventional interactions like lone pair (LP)⋯π and halogen bonding contacts. Another interesting motif is the formation of centrosymmetric R 22 (12) motifs where the cyano groups concurrently establish H-bonds and antiparallel CN⋯CN interactions. [ABSTRACT FROM AUTHOR]

Unraveling the binding preferences involved in the formation of a supramolecular complex is key to properly understand molecular recognition and aggregation phenomena, which are of pivotal importance to biology. The halogenation of nucleic acids has been routinely carried out for decades to assist in their X-ray diffraction analysis. The incorporation of a halogen atom on a DNA/RNA base not only affected its electronic distribution, but also expanded the noncovalent interactions toolbox beyond the classical hydrogen bond (HB) by incorporating the halogen bond (HalB). In this regard, an inspection of the Protein Data Bank (PDB) revealed 187 structures involving halogenated nucleic acids (either unbound or bound to a protein) where at least 1 base pair (BP) exhibited halogenation. Herein, we were interested in disclosing the strength and binding preferences of halogenated A···U and G···C BPs, which are predominant in halogenated nucleic acids. To achieve that, computations at the RI-MP2/def2-TZVP level of theory together with state of the art theoretical modeling tools (including the computation of molecular electrostatic potential (MEP) surfaces, the quantum theory of "Atoms in Molecules" (QTAIM) and the non-covalent interactions plot (NCIplot) analyses) allowed for the characterization of the HB and HalB complexes studied herein. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

It has been proposed that late transition metals with low coordination numbers (square planar or linear) can act as nucleophiles and participate in σ-hole interactions as electron donors. This is due to the existence, in this type of metal complexes, of a pair of electrons located at high energy d-orbitals (dz2 or dx2-y2), which are adequate for interacting with antibonding σ-orbitals [σ*(X–Y)] where Y is usually an electron withdrawing element and X an element of the p-block. This type of d[M]→σ*(X–Y) interaction has been reported for metals of groups 9–11 in oxidation states +1 and +2 (d8 and d10) as electron donors and σ-holes located in halogen and chalcogen atoms as electron acceptors. To our knowledge, it has not been described for σ-holes located in pnictogen atoms. In this manuscript, evidence for the existence of pnictogen bonding involving the square planar Pt(II) metal as the electron donor and Sb as the electron acceptor is provided by using an X-ray structure retrieved from the Cambridge Structural Database (CSD) and theoretical calculations. In particular, the quantum theory of atoms in molecules (QTAIM), the noncovalent interaction plot (NCIPlot) and molecular electrostatic potential (MEP) methods were used. Moreover, to further confirm the nature of the Sb···Pt(II) contact, a recently developed method was used where the electron density (ED) and electrostatic potential (ESP) distribution were compared along the Sb···Pt(II) bond path. [ABSTRACT FROM AUTHOR]

The series of substituted 1,2,4-selenodiazolium tetraphenylborate complexes were synthesized via cyclization between 2-pyridylselenylchloride, followed by the anion metathesis, and fully characterized. The utilization of tetraphenylborate anion, a strong π-electron donor via its phenyl rings, promoted the formation of assemblies exhibiting selenium–π interactions. The chalcogen bonding (ChB) interactions involving the π-systems of the tetraphenylborate anion were studied using density functional theory (DFT) calculations, where "mutated" anions were used to estimate the strength of the Se···π chalcogen bonds. Moreover, molecular electrostatic potential (MEP) surfaces were used to investigate the electron-rich and poor regions of the ion pairs. The quantum theory of atoms-in-molecules (QTAIM) and the noncovalent interaction (NCI) plot methods based on the topology of the electron density were used and combined to characterize the ChBs. The investigation reported herein disclosed that the formation of symmetrical dimers can be broken by the introduction of a stronger π-acceptor and, consequently, forming stronger Se···π contacts with selenodiazolium cations. [ABSTRACT FROM AUTHOR]

The series of benzylic-substituted 1,2,4-selenodiazolium salts were prepared via cyclization reaction between 2-pyridylselenyl chlorides and nitriles and fully characterized. Substitution of the Cl anion by weakly binding anions promoted the formation supramolecular dimers featuring four center Se2N2 chalcogen bonding and two antiparallel selenium⋯π interactions. Chalcogen bonding interactions were studied using density functional theory calculations, molecular electrostatic potential (MEP) surfaces, the quantum theory of atoms-in-molecules (QTAIM), and the noncovalent interaction (NCI) plot. The investigations revealed fundamental role of the selenium⋯π contacts that are stronger than the Se⋯N interactions in supramolecular dimers. Importantly, described herein, the benzylic substitution approach can be utilized for reliable supramolecular dimerization of selenodiazolium cations in the solid state, which can be employed in supramolecular engineering. [ABSTRACT FROM AUTHOR]

The synthetic protocol and solid state characterization of two new coumarin‐pyrazolylthiazole hybrids (1‐2) are detailed in this manuscript. Synthesized compounds were characterized applying nuclear magnetic resonance, Fourier‐transform infrared spectroscopy and single‐crystal X‐ray diffraction techniques. A detailed structural analysis of 3‐(2‐(5‐(4‐bromophenyl)‐3‐(4‐fluorophenyl)‐4,5‐dihydropyrazol‐1‐yl)thiazol‐4‐yl)‐2H‐chromen‐2‐one (1) and 3‐(2‐(3,5‐bis(4‐bromophenyl)‐4,5‐dihydropyrazol‐1‐yl)thiazol‐4‐yl)‐2H‐chromen‐2‐one (2) is reported along with a detailed description of the noncovalent interactions and their evaluation using Hirshfeld surface analysis, emphasizing the structure‐directing role of C−H⋅⋅⋅O, Br⋅⋅⋅π and π–π interactions. Finally, DFT energetics, molecular electrostatic potential (MEP), quantum theory of "atoms‐in‐molecules" (QTAIM) and noncovalent interaction plot (NCIplot) index computations have been used to further investigate the relative importance of two different π‐stacking complexes observed in the solid state of both compounds, which are recurrent binding motifs in their crystal packing. [ABSTRACT FROM AUTHOR]

This manuscript reports the synthesis, X-ray characterization and DFT study of a series of all-cis 3a,6 : 4,5 : 7,9a-triepoxy and 3a,6 : 7,9a-diepoxybenzo[de]isoquinolines obtained by the tandem intramolecular [4 + 2]/[4 + 2] cycloaddition in bis-furans (the IMDAF reaction) between difurfurylamine derivatives and dimethyl acetylenedicarboxylate (DMAD) as a dienophile. In one compound instead of DMAD, 1-phenyl-1H-pyrrole-2,5-dione (N-phenylmaleimide) was used as a dienophile. The existence of a "through-space" alpha-effect is analyzed in these compounds, since in three of them N–H⋯O2 H-bonds are observed in the solid state promoting the formation of self-assembled dimers. That is, the close O⋯O distance between the O-bridge atoms due to the rigidity of these molecules causes a lone pair⋯lone pair (LP⋯LP) interaction that enhances the H-bond acceptor ability of the bridging atoms (through-space α-effect). This fact has been studied using DFT calculations, molecular electrostatic potential (MEP) surfaces, electron localization function (ELF), quantum theory of atoms-in-molecules (QTAIM) and noncovalent interaction plot (NCIplot) index computational tools. This is the third study of the literature where "α-effect" hydrogen bonds (AEHBs) are described. The novelty of the present work resides in the utilization of an amine linker between the furan rings that allows the incorporation of a good H-bond donor in the model system. As a result, NH⋯O2 instead of CH⋯O2 AEHBs described in previous works are established. The X-ray analyses of the synthesized di- and tri-epoxides reveal that the AEHBs are predominant in the X-ray architecture of these compounds. [ABSTRACT FROM AUTHOR]

A bent trinuclear zinc complex, [Zn{ZnIL}2]·DMF {H2L = 2,2′-[(2,2-dimethyl-1,3-propanediyl)bis(iminomethylene)]bis[6-methoxyphenol]}, was synthesized and characterized using standard spectroscopic methods and X-ray diffraction analysis. The existence of coordinated amino groups and iodide counter ions provides the system with strong H-bond donor and acceptor groups that dictate the formation of 1D supramolecular assemblies in the solid state. These have been analysed using Hirshfeld surface analysis and DFT calculations. Dimerization energies have been found to be very large for the homodimer and the heterodimer, extracted from the infinite 1D chain. They have also been characterized and rationalized using molecular electrostatic potential (MEP) and non-covalent interaction plot (NCI plot) computational tools. Finally, the Cambridge Structural Database (CSD) has been analysed to compare the assemblies observed in [Zn{ZnIL}2]·DMF with those already published to resolve confusion on the NH⋯I interactions. [ABSTRACT FROM AUTHOR]

In this work, we report on new heteroleptic coordination compounds, [Pb2(LI)2](NO3)2·2MeOH (1), [Pb2(LII)2](NO3)2 (2), [Pb2(LIII)2](NO3)2·MeOH·H2O (3) and [Pb2(LIII)2(H2O)](NCS)2 (4), which were obtained through self-assembly of 2-(amino(pyridin-2-yl)methylene)hydrazine-1-carbothioamide (HLI), 2-(amino(pyrazin-2-yl)methylene)hydrazine-1-carbothioamide (HLII) or 2-(amino(pyridin-2-yl)methylene)-N-methylhydrazine-1-carbothioamide (HLIII) with Pb(NO3)2 or a mixture of Pb(ClO4)2 and KNCS, respectively. In all the obtained complexes, the lead(II) cation is N,N′,S-chelated by the tridentate pincer type monodeprotonated ligand LI–III. In addition to the thiosemicarbazone chelation, the sulfur atom in each structure acts as a bridge connecting two [Pb(LI–III)]+ units to form a dinuclear dimeric species having a centrosymmetric geometry, so that the ligands are directed either at different, in 1 and 2, or the same, in 3 and 4, sides of the coplanar Pb2S2 core. In the latter structures, two metal centers are additionally linked with each other through the oxygen atom of the bridging water molecule. The dimeric units in 1–4 are further linked through the Pb–N tetrel bonds, yielding 1D supramolecular polymeric chains, which, in turn, are interlinked though a myriad of other intermolecular noncovalent interactions, including tetrel bonds, hydrogen bonds and π-stacking. Counterions (NO3− and NCS−) and co-crystallized solvent molecules (MeOH and H2O) are also responsible in the further stabilization of the overall crystal packing of the obtained complexes as sources of either tetrel and/or hydrogen bonds. The observation of the recurrent tetrel bonds in compounds 1–4 has been rationalized using DFT calculations and molecular electrostatic potential (MEP) surface plots. Moreover, coordination bonds (covalent character) and tetrel bonds (noncovalent character) between the complexes and their counterions (and water molecules) have been differentiated using the quantum theory of "atoms-in-molecules" (QTAIM) and the noncovalent interaction index (NCI index) computational methods. [ABSTRACT FROM AUTHOR]

This manuscript reports the synthesis, X-ray characterization and DFT study of a series of all-cis 1,4:2,3:5,8:6,7-tetraepoxynaphthalenes (decahydro-2,6:3,5-diepoxynaphtho[2,3-b:6,7-b′]bis(oxirene) derivatives) obtained by the tandem [4 + 2] cycloaddition between dimethyl acetylenedicarboxylate (DMAD) and three difurans as bis-dienes (the IMDAF reaction). The "pincer"-type adduct formation is controlled by using kinetic conditions. For this work, we were only interested in the synthesis of "pincer"-type adducts to study the formation self-assembled dimers that are governed by quite short C–H⋯O H-bonds. The existence of the "through-space" alpha-effect in the "pincer"-type adducts increases their ability to establish bifurcated C–H⋯O2 H-bonds in the solid state. That is, the close distance between the O-bridge atoms provokes an interesting through space lone pair⋯lone pair (LP⋯LP) interaction that increases the H-bond acceptor ability of the O-atoms. It has been analyzed using DFT calculations, molecular electrostatic potential (MEP) surfaces, quantum theory of atoms-in-molecules (QTAIM) and noncovalent interaction plot (NCIplot) index computational tools. This is the second study of the literature where "alpha-effect" hydrogen bonds (AEHBs) are described and studied. The novelty of the present work resides in the exhaustive epoxidation of the double bonds in the resulting "pincer"-type adducts that increases the number of possible H-bond acceptors in the target vicinal tetra-epoxynaphthalenes. The X-ray analyses of the three synthesized tetra-epoxides reveal that the AEHBs are predominant in the solid phase. [ABSTRACT FROM AUTHOR]

An interplay between 4‐bromo‐ and 4‐iodo‐5‐nitrophthalonitriles (XNPN, X=Br or I) and any one of the azines (pyridine 1, 4‐dimethylaminopyridine 2, isoquinoline 3, 4‐cyanopyridine 4, 2‐methylpyridine 5, 2‐aminopyridine 6, quinoline 7, 1‐methylisoquinoline 8, and 2,2'‐bipyridine 9) proceeds differently depending on steric and electronic effects of the heterocycles. Sterically unhindered azines 1–3 underwent N‐arylation to give the corresponding azinium salts (characterized by 1H and 13C{H} NMR and high‐resolution ESI‐MS). In contrast, azines 4–9 with sterically hindered N atoms or bearing an electron‐withdrawing substituent, form stable co‐crystals with XNPN, where two interacting molecules are bound by halogen bonding. In all obtained co‐crystals, X⋅⋅⋅N structure‐directed halogen bonds were recognized and theoretically evaluated including DFT calculations (PBE0‐D3/def2‐TZVP level of theory), QTAIM analysis, molecular electrostatic potential surfaces, and noncovalent interaction plot index. Estimated energies of halogen bonding vary from −7.6 kcal/mol (for 6 ⋅ INPN) to −11.4 kcal/mol (5 ⋅ INPN). [ABSTRACT FROM AUTHOR]

A Cu(II) complex [CuL] of an asymmetrically di-condensed N2O2 donor Schiff base ligand, N-α-methylsalicylidene-N′-salicylidene-1,3-propanediamine (H2L) has been employed towards the synthesis of four heterometallic complexes, [(CuL)2Zn(N(CN)2)2] (1) [(CuL)2Cd(N(CN)2)2] (2), [(CuL)2Zn(SCN)2]·CH3CN (3) and [(CuL)2Cd(SCN)(H2O)]·ClO4 (4). All four complexes are found to be discrete bent trinuclear where two [CuL] units are coordinated to the central metal ion (Zn/Cd) via phenoxido oxygen atoms. In addition to two double phenoxido bridges, two monodentate dicyanamide ions in 1 and 2, two N-bonded thiocyanate in 3 and one S-bonded thiocyanate and one water molecule in 4 complete the hexa-coordination around the central metal ions. Recurrent π(arene)⋯π(chelate ring) stacked motifs were detected in the solid state of all complexes that have been studied by means of DFT calculations, rationalized using molecular electrostatic potential (MEP) surface calculations and characterized using the noncovalent interaction plot (NCIplot). The data presented herein show that the π(arene)⋯π(chelate ring) stacking interactions in complexes 1–4 are strong and relevant for determining their crystal packing. [ABSTRACT FROM AUTHOR]

[Display omitted] • A new nickel(II) complex of unsymmetrical Schiff base ligand has been synthesized and use it as a metalloligand. • Three new heterometallic nickel(II)-manganese(II) complexes have been synthesized. • All of the complexes have been structurally characterized. • The metalloligand shows variable denticity towards complex formations. • Presence of noncovalent interactions have been observed in all the complexes. An attempt to synthesis complexes of a N 2 O 3 donor unsymmetrical Schiff base ligand, obtained from the condensation of 2,2-dimethyl-1,3-propanediamine with o-hydroxyacetophenone and o-vanillin via modified Edler's method yielded a mononuclear Ni(II) complex, [NiL]·1.5H 2 O·0.5CH 3 OH (1), where H 2 L = N-(α-methylsalicylidene)-N′-(3-methoxysalicylidene)-2,2-dimethyl-1,3-propanediamine. Three heterometallic Ni(II)-Mn(II) complexes, [(NiL) 2 Mn(H 2 O) 2 ](ClO 4) 2 ·2H 2 O (2), [(NiL)MnCl 2 ] (3) and [(NiL)Mn(NCS) 2 (H 2 O)]·[NiL] (4), have been isolated upon reaction of complex 1 with Mn(II) ions in presence respective co-anions, of which two are discrete complexes while third is a co-crystal. Single crystal X-ray crystallography revealed that Ni(II) centre is four coordinated in square planar environment in all complexes, whereas the geometry of Mn(II) centre is distorted octahedral in complexes 2 and 4, and distorted trigonal bipyramidal in 3. Structural differences have been rationalized by density functional theory (DFT) calculations. All the complexes exhibit recurrent π-stacking and C H⋯π motifs in solid state which have been characterized by molecular electrostatic potential (MEP) surface calculations and non-covalent interaction plot. [ABSTRACT FROM AUTHOR]

This manuscript reports the synthesis and X-ray characterization of two octahydro-1H-4,6-epoxycyclopenta[c]pyridin-1-one derivatives that contain the four most abundant halogen atoms (Ha) in the structure with the aim of studying the formation of Ha···Ha halogen bonding interactions. The anisotropy of electron density at the heavier halogen atoms provokes the formation of multiple Ha···Ha contacts in the solid state. That is, the heavier Ha-atoms exhibit a region of positive electrostatic potential (σ-hole) along the C–Ha bond and a belt of negative electrostatic potential (σ-lumps) around the atoms. The halogen bonding assemblies in both compounds were analyzed using density functional theory (DFT) calculations, molecular electrostatic potential (MEP) surfaces, the quantum theory of "atom-in-molecules" (QTAIM), the noncovalent interaction plot (NCIplot), and the electron localization function (ELF). [ABSTRACT FROM AUTHOR]

• Fumarato and succinato bridged Co(II) and Ni(II) polymers. • Unusual N(nitrile)∙∙∙π(fum) and antiparallel CN⋯CN interactions. • Inclusion of (H 2 O) 2 cores within supramolecular host cavities. • DFT calculations in combination with NCI plot/QTAIM analysis. • Energetically significant structure-guiding non-covalent interactions. Two new Co(II) and Ni(II) coordination polymers viz. [Co(H 2 O) 2 (μ-fum)(3-CNpy) 2 ] n (1) and {[Ni(H 2 O) 2 (μ-succ)(4-CNpy) 2 ]·2H 2 O} 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 (H 2 O) 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. [Display omitted] Fumarato and succinato bridged coordination polymers of Co(II) and Ni(II) involving energetically significant structure guiding N(nitrile)∙∙∙π(fum), antiparallel nitrile∙∙∙nitrile and aromatic π-stacking interactions. [ABSTRACT FROM AUTHOR]

Three dinuclear cobalt(III/II) mixed valence reduced Schiff base complexes have been synthesized and characterized. Supramolecular assemblies observed in the solid state of the three complexes involving the pseudohalide as electron donors have been analysed using DFT calculations, MEP surfaces and characterized using the NCI Plot index. [Display omitted] Three dinuclear cobalt(III/II) mixed valence reduced Schiff base complexes, [(N 3)CoIIIL(μ-O 2 CR1)CoII(N 3)] ( 1 ), [(SCN)CoIIIL(μ-O 2 CR2)CoII(NCS)] ( 2 ) and [(SCN)CoIIIL(μ-O 2 CR3)CoII(NCS)] ( 3 ) {H 2 L= (2,2-dimethyl-1,3-propanediyl)bis(iminomethylene)bis(6-ethoxyphenol); R1CO 2 H = 4-methyl-3-nitrobenzoic acid; R2CO 2 H = benzoic acid; R3CO 2 H = 3-methyl-4-nitrobenzoic acid} have been synthesized and characterized by elemental analysis and spectral study. X-ray diffraction analysis was used to determine the structures of all three complexes. Spin density calculations have been used to determine the location of the paramagnetic cobalt(II) center in each of the dinuclear complexes. Moreover, several supramolecular assemblies (formed by CH⋯O, CH···SCN and S··· π and other interactions) observed in the solid state of the three complexes involving the pseudohalide as electron donors have been analysed using DFT calculations, molecular electrostatic potential (MEP) surfaces and characterized using the noncovalent interaction plot (NCI Plot) index. [ABSTRACT FROM AUTHOR]

• Investigation of noncovalent interactions in tetrahydrocarbazole-carbonitrile scaffold. • Understanding the role of O H...N, N H...O, C H...π and π...π interactions. • Visualization of NCIs using molecular electrostatic potential. • Unraveling the energetic features of NCIs using QTAIM and NCIPlot methods. • In vitro urease inhibition evaluation revealing a 4-fold strong efficacy. • Binding mode analysis and computation of pharmacokinetic properties. Organic crystals hold a significant importance in pharmaceuticals, biological systems and functional materials. In the present study, a tricyclic aromatic structure, tetrahydrocarbazole (THC), incorporating a nitrile functionality was synthesized via the Fischer indolization of 4-hydroxycyclohexanone with 4-hydrazinobenzonitrile hydrochloride in 70% yield. The detailed description of noncovalent interactions of various types and strengths in the crystal structure of tetrahydrocarbazole-carbonitrile was investigated using a combination of experimental and theoretical methods. The supramolecular assembly of THC involved the extensive network of N H...O and O H...N hydrogen bonds, and weaker π...π and C H...π contacts. The nature of noncovalent interactions was visualized using molecular electrostatic potential whereas QTAIM and NCIPlot methods revealed the energetic features of π-stacking and H-bonding in the supramolecular assemblies of tetrahydrocarbazole-carbonitrile. In vitro evaluation of urease inhibitory potential of target compound revealed a 4-fold strong inhibition (IC 50 = 5.26 ± 0.10 µM) compared to standard drug (thiourea; IC 50 = 22.3 ± 1.06 µM). Finally, molecular docking analysis showed significant interactions of target compound with various active site amino acids of Jack bean urease. Combined QTAIM and NCIplot analyses of an H-bonded trimer (a) and an antiparallel self-assembled dimer (b) of 3 are described. [Display omitted] [ABSTRACT FROM AUTHOR]