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Two novel supramolecular heteroleptic complexes [Pb2L2(NO3)2]n (1) and {[Pb3L3](ClO4)3}n·3.25nH2O (2·3.25nH2O), obtained from N′-(piperidine-1-carbonothioyl)picolinohydrazonamide (HL) and Pb(NO3)2 or Pb(ClO4)2 in aqueous methanol are reported. A crucial role of the auxiliary ligand (NO3−vs. ClO4−) was revealed as a driving force for the formation of the resulting architecture of complexes, which, in turn, are dictated by the formation of tetrel bonds. Complex 1 is constructed from heteroleptic dinuclear centrosymmetric species [Pb2L2(NO3)2], which, in turn, are formed from the heteroleptic mononuclear symmetry related [PbL(NO3)] units, linked through a pair of bonds formed between the metal cations and the thioamide nitrogen atoms. The metal cations form a weaker tetrel bond with the symmetry related nitrate atoms, yielding a 1D polymeric chain structure. These chains are interlinked through N–H⋯O hydrogen bonds, formed between the covalently coordinated nitrate oxygen atom and the NH2 hydrogen atom, yielding a 2D supramolecular architecture. Complex 2·3.25nH2O is constructed from the trinuclear species [Pb3L3](ClO4)3. The trinuclear cation is constructed from three [PbL]+ cations interlinked through two Pb–S and two Pb–N bonds, formed with the thiocarbonyl sulfur atoms and the amide nitrogen atoms. The cations [Pb3L3]3+ are interlinked through two Pb–N and two Pb–S bonds yielding a 1D supramolecular polymeric cationic chain {[Pb3L3]3+}n. The two metal cations corresponding to two [PbL]+ units, linked through a pair of the Pb–S bonds, are additionally bridged by two oxygen atoms of one of the perchlorate anions with the formation of two Pb⋯O tetrel bonds. The coordination spheres of the metal cations are filled by one of the oxygen atoms of two different perchlorate anions with the formation of tetrel bonds. One of these perchlorates also forms the N–H⋯O hydrogen bond within the trinuclear unit [Pb3L3](ClO4)3. 1D supramolecular chains {[Pb3L3]3+}n are interlinked through a myriad of hydrogen bonds formed by the perchlorate anions and crystallized water molecules. The tetrel bonds involving the counterions (Pb⋯O) have been also analysed by DFT calculations via a MEP surface plot and 2D maps of electron localization function (ELF), Laplacian of electron density (∇2ρ) and reduced density gradient (RDG), confirming their noncovalent nature. [ABSTRACT FROM AUTHOR]

In this contribution, a novel binuclear heteroleptic complex [Pb2L2(CO3)]·2CH3CN·2MeOH (1·2CH3CN·2MeOH) is reported, which was fabricated by electrochemical oxidation of a lead anode under an ambient atmosphere in a CH3CN : MeOH solution of N′-isonicotinoylpyrazine-2-carbohydrazonamide (HL). The CO32− anion was produced from the conversion of aerial CO2 by the Pb2+–L complex system under electrochemical conditions. In the structure of 1, ligand L exhibits a tridentate pincer-like N,N′,O-coordination mode, while the CO32− anion exhibits a tetradentate bridging coordination mode with one of the oxygen atoms exhibiting a bridging μ-coordination mode. The metal cations in the structure of 1 are in a five-membered N2O3 coordination environment, formed by covalent bonds. The molecular structure of 1·2CH3CN·2MeOH is stabilized by a pair of intermolecular Pb⋯N tetrel bonds formed with one of the NH2 nitrogen atoms of an adjacent complex molecule and with the acetonitrile nitrogen atom, and one Pb⋯O tetrel bond formed with the carbonyl oxygen atom of the other adjacent complex molecule, yielding a 2D supramolecular sheet. This sheet is further stabilized by intermolecular N–H⋯Nacetonitrile and N–H⋯Ocarbonate hydrogen bonds and πPyrazine⋯πPyridine interactions. The optical properties of the complex were revealed by UV-vis spectroscopy and spectrofluorimetry in MeOH. It was established that the described complex is emissive upon excitation at 340 nm with a broad band from about 500 nm to 780 nm with a maximum at ∼580 nm, accompanied by a shoulder at ∼620 nm. The CIE-1931 chromaticity coordinates of (0.28, 0.36) fall within the white gamut of the chromaticity diagram. Thus, complex 1 is a single-component white light-emitting phosphor. [ABSTRACT FROM AUTHOR]

The co-crystallization of S-(CF3)-dibenzothiophenium ("Umemoto" – abbreviated Ume) cations and polycyanometalates with different coordination geometries yields a large structural variety of supramolecular assemblies. In the case of [Ume+]2[Ni(CN)4]2−·CH2Cl2 all four cyanide groups of the square-planar dianion act as chalcogen bond acceptors whereas the sulfur atoms of the Umemoto cations act as biaxial chalcogen bond donors. For tetrahedral [Zn(CN)4]2− a more complex assembly of four Umemoto cations and two dianions is observed. In the case of [Ume+]3[Fe(CN)6]3−·CH2Cl2 one Umemoto cation even acts as a triaxial chalcogen bond donor whereas only 4 out of the 6 cyanide groups act as chalcogen bond acceptors. For [Ume+]3[W(CN)8]3− a polymeric chain structure is observed in which all Umemoto cations act as biaxial chalcogen bond donors. DFT investigations focus on the physical nature of the chalcogen bonds, encompassing energetic assessments, MEP surface plots, QTAIM, and NBO analysis, shedding light on the nature of chalcogen donor–acceptor interactions. The energetic results evidence that total contributions of chalcogen bonds in different synthons range from −7.6 to −16.3 kcal mol−1, surpassing that of hydrogen bonds that range from −4.9 to −11.8 kcal mol−1. [ABSTRACT FROM AUTHOR]

This study delves into the intriguing realm of chalcogen-bonding interactions, specifically focusing on tellurium(II) and/or tellurium(IV) interactions with iodide species within six crystals. Utilising comprehensive computational chemistry calculations and underpinned by crystallographic data retrieved from the Cambridge Structural Database, this research elucidates the supramolecular aggregation, bonding nature and interaction energetics of Te...I non-covalent bonds in a series of crystals containing each of tellurium(II), tellurium(IV) and iodide. The investigation encompasses a variety of molecular assemblies, ranging from zero-dimensional to complex three-dimensional architectures. Tellurium(II) atoms formed Te...I interactions in six of the crystals but tellurium(IV) participated in Te...I interactions in only three crystals despite there being equal numbers of tellurium(II) and tellurium(IV) atoms in the zero- and onedimensional assemblies. Several computational tools, including Molecular Electrostatic Potential (MEP) surfaces, Quantum Theory of Atoms in Molecules (QTAIM) and Natural Bond Orbital (NBO) analyses, provide a nuanced understanding of the electron density topology and charge transfer mechanisms. In some assemblies, where the Te...I interactions are ~3.2 Å, the interaction energies are very large, i.e. 25.6 to 38.8 kcal mol-1, suggesting partial covalent character, an observation corroborated by the NBO analysis; longer Te...I separations correlate with reduced energies, i.e. 3.1 to 7.0 kcal mol-1. Crucially, it is noteworthy that the Te...I interactions identified in this study are distinctly characterised as chalcogen bonds, rather than halogen bonds. [ABSTRACT FROM AUTHOR]

The X-ray structure of 2-(dibromomethyl)benzonitrile, featuring unexpectedly short C≡N⋯Br halogen bond distances between a nitrile group and a C(sp3)-linked bromine atom, is presented. Despite the weak Lewis base nature of the nitrile N atom and absence of strong electron-withdrawing groups on the Br atom, π-stacking significantly enhances both the electron donor and acceptor capability of the interacting partners. As such, and beyond trivial (hetero)aromatic systems, the rationale of C ≡N⋯B r halogen bonding can also be employed in purely aliphatic systems. [ABSTRACT FROM AUTHOR]

Three new PbII complexes [Pb(LI)(SCN)]n, {[Pb(LII)](SCN)}n and {[Pb(HLIII)(SCN)](SCN)}n (HLI = N′-phenyl(pyridin-2-yl)methylene-N-phenylthiosemicarbazide, HLII = N′-amino(pyrazin-2-yl)methylenethiosemicarbazide, HLIII = N′-amino(pyridin-2-yl)methylenethiosemicarbazide) have been synthesized and characterized by spectroscopic techniques and single crystal X-ray diffraction. In all complexes, the corresponding organic ligand behaves as a tridentate N,N′,S-chelating species. A 1D supramolecular polymeric aggregation in complex [Pb(LI)(SCN)]n is dictated by the Pb⋯NCS and Pb⋯S＝C tetrel bonds formed between the [Pb(LI)(SCN)] species. 1D cationic coordination polymers ([Pb(LII)])nn+ in the structure of complex {[Pb(LII)](SCN)}n are linked into a 2D supramolecular polymeric layer through the Pb⋯NCS tetrel bonds and Pb⋯π(NCS) interactions formed with the nitrogen atom and the conjugated system of the free SCN− anions, respectively. The cationic species [Pb(HLIII)(SCN)]+ in the structure of complex {[Pb(HLIII)(SCN)](SCN)}n produce a 1D supramolecular polymer due to the Pb⋯SCN and Pb⋯S＝C tetrel bonds, further stabilized by the Pb⋯π(NCS) interactions formed with the conjugated system of the coordinated NCS− anion. The latter anions also link these 1D chains through the Pb⋯SCN tetrel bonds, yielding 1D supramolecular polymeric ribbons. The energetic relevance of the Pb⋯S and Pb⋯N tetrel bonds has been studied by DFT calculations. The tetrel bonds have been characterized using QTAIM and NCIplot analysis and rationalized using molecular electrostatic potential surface calculations. [ABSTRACT FROM AUTHOR]

Three new 1,3,4-oxadiazoles (1–3) have been synthesized. The crystal structure of two of them were solved by single crystal X-ray diffraction analysis and a detailed quantitative analysis of the weak noncovalent interactions have been performed by using DFT calculations. In both compounds, the formation of recurrent H-bonded motifs involving the 1,3,4-oxadiazole is observed. In addition, a variety of CH⋯π interactions are established, involving both aliphatic and aromatic C–H bonds and the π-system of the electron rich tert-butylphenyl ring. QTAIM analysis and NCI plots were used to study the nature and the extent of different intermolecular interactions observed in these structures, which were rationalized using MEP surface plots. [ABSTRACT FROM AUTHOR]

Two new metal(II) complexes [M(dmv)2(py)2]·3H2O {M = Ni (1), Zn (2)} were self-assembled from a metal(II) chloride salt, N,N′-dimethylvioluric acid (Hdmv), and pyridine (py). They were isolated as stable crystalline solids and characterized, including by single crystal X-ray diffraction. Structures 1 and 2 are composed of discrete [M(dmv)2(py)2] blocks in which the six-coordinate metal(II) atoms show a slightly distorted {MN4O2} octahedral geometry. The adjacent [M(dmv)2(py)2] units are hydrogen bonded with an involvement of disordered water clusters into 1D H-bonded chains. DFT calculations were used to analyse the unconventional anti-parallel C＝O⋯C＝O interaction observed between the monomeric units in 1 and 2. Complex 1 also refers to an elongated tetragonal bipyramid for which a positive zero-field splitting is confirmed by magnetic studies. The complex matches the magnetostructural D-correlation for hexacoordinate Ni(II) complexes with moderate structural and magnetic anisotropy with Dstr = +7.45 pm, and Dmag = +5.11 cm−1. Solution state NMR spectroscopy reveals a slow isomerization process related to the bidentate-N,O and bidentate-O,O coordination of dimethylviolurate in 2, with the barrier ranging from 76.4 to 77.9 kJ mol−1. The 1H NMR spectra confirm the presence of three water molecules which exhibit significant chemical shift dependence on temperature indicating strong binding to the complex in solution phase. [ABSTRACT FROM AUTHOR]

Novel nitronyl nitroxides, namely 2-(3-iodoethynylphenyl)- and 2-(4-iodoethynylphenyl)-4,4,5,5-tetramethyl-imidazoline-3-oxyl-1-oxides, were prepared by condensation of appropriate aldehydes with 2,3-bis(hydroxylamino)-2,3-dimethylbutane followed by oxidative treatment with NaIO4. Crystal and molecular structures of the obtained paramagnets were studied by single-crystal X-ray diffraction. In the crystals, the radicals are assembled into zigzag chains in which the radical building blocks are linked by intermolecular I⋯N–O halogen bonding. Magnetic analyses revealed that in both nitronyl nitroxides, the radicals are weakly coupled. Nonetheless, spin–spin interactions in the 3-iodoethynyl isomer are antiferromagnetic, and the coupling is stronger than that in the 4-iodoethynyl derivative, in which the exchange interaction is ferromagnetic. DFT calculations in combination with MEP, NCIplot, and QTAIM analyses were used to evaluate and characterize the structure-directing halogen bonding interactions observed in the solid state of both compounds. [ABSTRACT FROM AUTHOR]

We report the crystal structure of the anhydrous form of Oxyma-B, a relevant racemization suppressor for peptide synthesis, solved by direct space methodologies with X-Ray Powder Diffraction data. The structure had remained elusive since only monohydrate crystals are readily obtained from slow crystal growth experiments. An extensive combined experimental and computational study has allowed us to obtain deeper insight into the solid-state landscape of Oxyma-B and its tendency for hydration. The singular network of H-bonds and energetically relevant O⋯π interactions formed by the two symmetrically independent molecules of anhydrous Oxyma-B has been analysed by using the quantum theory of "atoms-in-molecules" (QTAIM) and the noncovalent interaction plot (NCIplot). [ABSTRACT FROM AUTHOR]

The Cambridge Structural Database was surveyed for crystals featuring Hg⋯S secondary-bonding interactions for mercury(II) compounds (excluding organomercury compounds). In all, 43 examples of crystals including intermolecular Hg⋯S interactions operating largely in isolation from other directional interactions were detected with the Hg⋯S interactions within zero-, one- and two-dimensional aggregation patterns. Over 50% of the aggregates are one-dimensional with topologies ranging from linear, zigzag and helical chains, and ribbons to tapes; 30% of the crystals exhibit zero-dimensional aggregates. Crucially, selected examples were subjected to DFT calculations with mapping of the molecular electrostatic potentials (MEPs) of the molecules as well as quantum theory of atoms in molecules (QTAIM), non-covalent interaction plot (NCIPLOT) and natural bond order (NBO) investigations. This study confirms the presence of σ-/π-holes or positive belts at the mercury atom depending on the coordination geometry, defined by covalently and non-covalently bound donor atoms. In molecules coordinated by sulphur donors, the σ-hole at the sulphur atom merges with the positive belt around the mercury atoms, assisting in the formation of spodium bonds and providing higher directionality. The QTAIM/NCIPLOT analysis supports both the existence and non-covalent nature of the spodium bonds. Finally, the NBO analysis reveals charge transfer effects indicating the existence of LP → σ* orbital interactions in the studied molecules; LP is a lone-pair. The energy of stabilisation provided by spodium bonds ranges from a low 3 kcal mol−1 to a high 19 kcal mol−1, i.e. values often greater than those by conventional hydrogen-bonding interactions. [ABSTRACT FROM AUTHOR]

Thallium compounds, i.e. Tl+[S2P{OC6H3(2,5-(CH3)2)}2]− (1) and Tl+[S2P{OC6H3(3,5-(CH3)2)}2]− (2), stabilized by intra- and intermolecular triel bonds were isolated and characterized by FT-IR, NMR (31P, 1H and 13C) spectroscopy, and SC-XRD analysis. The crystal structures of 1 and 2 belong to monoclinic crystal systems with the space group C2/c and P21/n, respectively. Interestingly, the positively charged Tl atom is bonded attractively with the π-holes of the 1,1-dithioate moiety. These compounds exist in ionic form and exhibit Tl⋯S and Tl⋯π contacts (TrBs), which assist the formation of unique supramolecular polymeric architectures owing to the stereochemically active lone pair of electrons and hemi-directed coordination sphere around thallium. A differentiating feature in compound 2 is the formation of a unique Tl⋯π/π⋯π/Tl⋯π self-assembly. The attractive nature of TrB was further confirmed by DFT calculations using the quantum theory of atoms-in-molecules (QTAIM) and non-covalent interaction plot (NCIPlot) index methods. A systematic Hirshfeld surfaces analysis was also carried out to compare the intermolecular interactions. [ABSTRACT FROM AUTHOR]

Optically-active luminescent materials based on lanthanoid ions attract significant attention due to their unique spectroscopic properties and the possibility of application as chemical sensors. Five isostructural lanthanoid metal organic frameworks, namely {[Pr(3,4-PDA)(Glu)0.5(H2O)2]CH3CN}(1) and [Ln(3,4-PDA)(Glu)0.5(H2O)2]: Ln = Nd (2), Sm (3), Eu (4), and Tb (5) (where 3,4-PDA = pyridine-3,4-dicarboxylic acid, Glu = glutaric acid), synthesized via the solvothermal method are reported. These lanthanoid metal–organic frameworks were characterized by FTIR, single-crystal X-ray diffraction, powder X-ray diffraction, BET, Hirshfeld surface analysis, DFT calculations, electronic spectroscopy, and photoluminescence techniques. MOFs 1–5 show porous two-dimensional (2D) structures. The luminescence properties of MOFs 4 and 5 demonstrated the range of sensing capabilities for some toxic heavy metals. However, MOFs 4 and 5 are highly sensitive for the detection of Pb2+, exhibiting the most effective luminescence quenching with the lowest detectable change in the signal occurring at ∼0.014 and ∼0.013 ppm of Pb2+ with MOFs 4 and 5, respectively, at room temperature in minutes. The MOF-based luminescence sensors designed in this paper demonstrate a successful and feasible strategy to use pyridine-3,4-dicarboxylic acid-based ligand as an antenna, which can efficiently sensitize Eu3+ and Tb3+ emission. MOFs 4 and 5 show great potential in the application of environmental detection of Pb2+ in water. [ABSTRACT FROM AUTHOR]

This study reports the synthesis and characterization of two closely related semicarbazone/thiosemicarbazone-based organic compounds: N-(2-hydroxy-3-methoxy-5-methylbenzylidene)semicarbazide (1) and N-(2-hydroxy-3-methoxy-5-methylbenzylidene)thiosemicarbazide (2). Structural studies revealed the conformational diversity in these systems as compound 1 crystallized as only one conformer, while compound 2 crystallized as a mixture of two conformers. DFT calculations in combination with the quantum theory of atoms in molecules (QTAIM) and natural bond orbital (NBO) analyses revealed that the energy difference between the two conformers was larger in compound 1, while the difference between both conformers was very small in the thiosemicarbazide derivative (2), in line with the X-ray crystallographic characterizations. The synthesized compounds were tested for their electrical conductivity behaviour via current density–voltage measurements, as well as impedance spectroscopy, which revealed that both compounds were semiconducting in nature, arising from the charge transport through space via π⋯π contacts, and could be useful for the fabrication of electrical devices, particularly 1, in which the conductivity fell by a higher order of magnitude than observed in similar organic semiconductors tested earlier. Moreover, the combined experimental and theoretical studies showed the importance of the non-covalent interactions on the stability of the different conformers, thereby guiding the possible isolations of different polymorphic forms of such conformationally diverse semicarbazone/thiosemicarbazone systems through the selective stabilization of a particular conformer by varying the reaction conditions. [ABSTRACT FROM AUTHOR]

A nickel(II)–zinc(II) complex, [(NiL)Zn(μ1,3-NCS)2]n (1), and a nickel(II)–mercury(II) complex, [{(NiL)Hg(μ1,3-SCN)(SCN)}2] (2), (where H2L = N,N′-bis(salicylidene)-1,3-propanediamine) were synthesized via a metalloligand approach, in which the former is a 2D coordination polymer and the latter is a discrete tetramer. Single-crystal X-ray crystallography revealed that Zn(II) in 1 and Hg(II) in 2 are in a four-coordinated distorted tetrahedral environment whereas the geometry of the Ni(II) centre is distorted octahedral for complex 1 but distorted square planar for complex 2. DFT calculations were used to analyze an intramolecular weak interaction between the square planar Ni(II) ion and the N-end of thiocyanate ions, which can be defined as a π-hole interaction. Moreover, we analyzed the tetranuclear structure of 2 in terms of a self-assembled dimer via the formation of two strong spodium bonds instead of Hg–N coordination bonds, as evidenced by the QTAIM and NCI plot analysis and the magnitude of the dimerization energy. [ABSTRACT FROM AUTHOR]

We report the discovery of new cocrystals of bosentan, a drug used in the treatment of pulmonary artery hypertension, with succinic acid, resorcinol, and 4-hydroxybenzoic acid through a combined virtual/experimental cocrystal screening. The X-ray structure of the bosentan/succinic acid cocrystal shows a network of H-bonds involving both components, which have been studied energetically using DFT calculations. The succinic acid molecules interact with one of the pyrazine rings of bosentan establishing an energetically significant lp⋯π interaction. Moreover, they form homodimers stabilized by antiparallel CO⋯CO interactions. This set of interactions has been rationalized using molecular electrostatic potential (MEP) surfaces, the quantum theory of "atoms-in-molecules" (QTAIM), and the noncovalent interaction plot (NCIplot). [ABSTRACT FROM AUTHOR]