Thiophene-Functionalized Cadmium(II)-Based Metal-Organic Frameworks for CO2 Adsorption with Gate-Opening Effect, Separation, and Catalytic Conversion.

Two new porous three-dimensional cadmium(II) metal-organic frameworks (MOFs) containing thiophene-appended carboxylate acid ligands, formulated as [Cd(L1)(4,4'-Bipy)]n.2n(DMF) (1) and [Cd(L2)(4,4'-Bipy)]n.2n(DMF) (2) [where L1 = 5-{(thiophen-2-ylmethyl)amino}isophthalate, L2 = 5-{(thiophen-3-ylmethyl)amino}isophthalate, 4,4'-Bipy = 4,4'-bipyridine, and DMF = N,N'-dimethylformamide] have been synthesized and structurally characterized. The gas adsorption analysis of the activated MOFs shows that they specifically capture CO2 (uptake amount 4.36 mmol/g under 1 bar at 195 K) over N2 and CH4. Moreover, both MOFs show a gate-opening-closing phenomenon, which features the S-shaped isotherms with impressive hysteretic desorption during the CO2 adsorption-desorption process at 195 K. Ideal adsorbed solution theory (IAST) calculations of these MOFs displayed that the obtained selectivity values for CO2/CH4 (50:50) and CO2/N2 (15:85) are approximately 8.6-23 and 93-565, respectively. Configurational bias Monte Carlo simulation was performed to understand the mechanism behind the better CO2 adsorption by these MOFs. Catalytic activity of the MOFs for the CO2 fixation reactions with different epoxides to form cyclic carbonates were tested. These MOFs demonstrated a significantly high conversion (94-99%) of epichlorohydrin to the corresponding cyclic carbonate within 8 h of reaction time at 1 bar of CO2 pressure, at 70 °C, and they can be reused up to five cycles without losing considerably their activity.

A new 1D Mn(II) coordination polymer: Synthesis, crystal structure, hirshfeld surface analysis and molecular docking studies.

The synthesis of novel metal-organic coordination polymers (MOCP) with the chemical formula [Mn2L (SCN)2(OH)2]3·CH3OH [L = 1,5-bis(pyridine-4-ylmethylene) carbonohydrazide] {1} was accomplished using two different techniques: solvothermal and sonochemical ultrasonic-assisted. An investigation was carried out to examine the impact of various factors such as reaction time, sonication power, temperature, and reactant concentration on the morphology and size of the crystals. Interestingly, it was found that sonication power and temperature did not affect the crystals' morphology and size. To further analyze the prepared microcrystals of MOCPs, SEM was utilized to examine their surface morphology, and XRD, elemental evaluation composition. The identification of the functional groups present in the prepared Mn-MOCPs was accomplished through the utilization of FT-IR spectroscopy. Subsequently, the calcination of 1 in an air atmosphere at 650 °C led to the formation of Mn3O4 nanoparticles. The geometric and electronic structure of the MOCPs was evaluated using density functional theory (DFT). The utilization of molecular docking methodologies demonstrated that the best cavity of the human androgen receptor possessed an interaction energy of -116.3 kJ mol-1. This energy encompassed a combination of both bonding and non-bonding interactions. The Results showed that steric interaction and electrostatic potential are the main interactions in AR polymer and Mn(II). These interactions in the defined cavity indicated that this polymer could be an effective anti-prostate candidate, because AR is involved in the growth of prostate cancer cells, and these interactions indicated the inhibition of prostate cancer cell growth.

Design, synthesis and anticancer evaluation of novel arylhydrazones of active methylene compounds.

Nerve growth factor (NGF) and its receptor, tropomyosin kinase receptor kinase type A (TrkA) is emerging as an important target for Glioblastoma (GBM) treatment. TrkA is the cancer biomarker majorly involved in tumor invasion and migration into nearby normal tissue. However, currently, available Trk inhibitors exhibit many adverse effects in cancer patients, thus demanding a novel class of ligands to regulate Trk signaling. Here, we exploited the role of TrkA (NTRK1) expression from the 651 datasets of brain tumors. RNA sequence analysis identified overexpression of NTRK1 in GBM, recurrent GBM as well in Oligoastrocytoma patients. Also, TrkA expression tends to increase over the higher grades of GBM. TrkA protein targeting hydrazone derivatives, R48, R142, and R234, were designed and their mode of interaction was studied using molecular docking and dynamic simulation studies. Ligands' stability and binding assessment reveals R48, 2 2-(2-(2-hydroxy-4-nitrophenyl) hydrazineylidene)-1-phenylbutane-1,3-dione, as a potent ligand that interacts well with TrkA's hydrophobic residues, Ile, Phe, Leu, Ala, and Val. R48- TrkA exhibits stable binding potentials with an average RMSD value <0.8 nm. R48 obeyed Lipinski's rule of five and possessed the best oral bioavailability, suggesting R48 as a potential compound with drug-likeness properties. In-vitro analysis also revealed that R48 exhibited a higher cytotoxicity effect for U87 GBM cells than TMZ with the IC50 value of 68.99 µM. It showed the lowest percentage of cytotoxicity to the non-cancerous TrkA expressing MEF cells. However, further SiRNA analysis validates the non-specific binding of R48, necessitating structural alteration for the development of R48-based TrkA inhibitor for GBM therapeutics.

Halogen Bonding in the Decoration of Secondary Coordination Sphere of Zinc(II) and Cadmium(II) Complexes: Catalytic Application in Cycloaddition Reaction of CO2 with Epoxides.

Three new zinc(II) complexes [Zn(H2L3)2(H2O)3] (Zn2), [Zn(H3L2a)(H2O)3]n (Zn3) (H3L2a = 2,4-diiodo-5-(2-(2,4,6-trioxotetrahydropyrimidin-5(2H)-ylidene)hydrazineyl)isophthalate) and [Zn(HL4)(DMF)(H2O)]n (Zn4) were synthesized by the reaction of Zn(II) salts with 5-(2-(2,4-dioxopentan-3-ylidene)hydrazineyl) isophthalic acid (H3L3), 2,4,6-triiodo-5-(2-(2,4,6-trioxotetrahydropyrimidin-5(2H)-ylidene)hydrazineyl) isophthalic acid (H5L2) (in the presence of NH2OH·HCl) and 5-(2-(2,4-dioxopentan-3-ylidene)hydrazineyl)-2,4,6-triiodoisophthalic acid (H3L4), respectively. According to the X-ray structural analysis, the intramolecular resonance-assisted hydrogen bond ring remains intact, with N···O distances of 2.562(5) and 2.573(5) Å in Zn2, 2.603(6) Å in Zn3, and 2.563(8) Å in Zn4. In the crystal packing of Zn3, the cooperation of I···O and I···I types of halogen bonds between tectons leads to a one-dimensional supramolecular polymer, while I···O interactions aggregate 1D chains of coordination polymer Zn4. These new complexes (Zn2, Zn3, and Zn4) and known [Zn(H3L1)(H2O)2]n (Zn1) (H3L1 = 5-(2-(2,4,6-trioxotetrahydropyrimidin-5(2H)-ylidene) hydrazineyl)isophthalate), {[Zn(H3L1)(H2O)3]·3H2O}n (Zn5), [Cd(H3L1)(H2O)2]n (Cd1), {[Cd(HL3)(H2O)2(DMF)]·H2O}n (Cd2), [Cd(H3L3)]n (Cd-3), {[Cd2(µ-H2O)2(µ-H2L4)2(H2L4)2]·2H2O}n (Cd4), and {[Cd(H3L1)(H2O)3]·4H2O}n (Cd5) were tested as catalysts in the cycloaddition reaction of CO2 with epoxides in the presence of tetrabutylammonium halides as the cocatalyst. The halogen-bonded catalyst Zn4 is the most efficient one in the presence of tetrabutylammonium bromide by affording a high yield (85-99%) of cyclic carbonates under solvent-free conditions after 48 h at 40 bar and 80 °C.

Benzenesulfonamide Analogs: Synthesis, Anti-GBM Activity and Pharmacoprofiling.

The tropomyosin receptor kinase A (TrkA) family of receptor tyrosine kinases (RTKs) emerge as a potential target for glioblastoma (GBM) treatment. Benzenesulfonamide analogs were identified as kinase inhibitors possessing promising anticancer properties. In the present work, four known and two novel benzenesulfonamide derivatives were synthesized, and their inhibitory activities in TrkA overexpressing cells, U87 and MEF cells were investigated. The cytotoxic effect of benzenesulfonamide derivatives and cisplatin was determined using trypan blue exclusion assays. The mode of interaction of benzenesulfonamides with TrkA was predicted by docking and structural analysis. ADMET profiling was also performed for all compounds to calculate the drug likeness property. Appropriate QSAR models were developed for studying structure-activity relationships. Compound 4-[2-(4,4-dimethyl-2,6-dioxocyclohexylidene)hydrazinyl]-N-(5-methyl-1,3,4-thiadiazol-2-yl)benzenesulfon-amide (AL106) and 4-[2-(1,3-dioxo-1,3-dihydro-2H-inden-2-ylidene)hydrazinyl]-N-(5-methyl-1,3,4-thiadiazol-2-yl)benzenesulfonamide (AL107) showed acceptable binding energies with the active sites for human nerve growth factor receptor, TrkA. Here, AL106 was identified as a potential anti-GBM compound, with an IC50 value of 58.6 µM with a less toxic effect in non-cancerous cells than the known chemotherapeutic agent, cisplatin. In silico analysis indicated that AL106 formed prominent stabilizing hydrophobic interactions with Tyr359, Ser371, Ile374 and charged interactions with Gln369 of TrkA. Furthermore, in silico analysis of all benzenesulfonamide derivatives revealed that AL106 has good pharmacokinetics properties, drug likeness and toxicity profiles, suggesting the compound may be suitable for clinical trial. Thus, benzenesulfonamide analog, AL106 could potentially induce GBM cell death through its interaction with TrkA and might be an attractive strategy for developing a drug targeted therapy to treat glioblastoma.

Chalcogen bonding in copper(II)-mediated synthesis.

The chalcogen bond (ChB) is a noncovalent attraction between an electrophilic chalcogen atom and a nucleophilic (Nu) region in the same (intramolecular) or another (intermolecular) molecular entity: R-Ch⋯Nu (Ch = O, S, Se or Te; R = substituents; Nu = nucleophile). ChB is comparable to the hydrogen and halogen bonds both in terms of strengths and directionality. However, in contrast to the monovalent halogen atoms, usually the divalent or tetravalent chalcogen atoms are able to display more than one electrophilic centre (on account of the existence of two or three species bonded to the chalcogen atom), which provides an additional opportunity in the use of this type of noncovalent binding in synthetic operations. In this work, the role of ChB at the secondary coordination sphere of metal complexes through copper(II)-mediated activation of dioxygen or of one nitrile group of a 1,2,5-selenadiazole-3,4-dicarbonitrile ligand to form a carbimidate or an imino-carboxylic acid is demonstrated. DFT calculations allowed evaluation of the strength of the ChBs and proved their relevant structure directing role in the solid state architectures. The effect of metal-coordination on the σ-hole opposite to the coordinated SeO bond has been analysed using molecular electrostatic potential (MEP) surfaces and explains the greater ability of the coordinated selenoxide derivatives to form strong ChBs.

Correction: Solvent-driven azide-induced mononuclear discrete versus one-dimensional polymeric aromatic Möbius cadmium(II) complexes of an N6 tetradentate helical ligand.

Correction for 'Solvent-driven azide-induced mononuclear discrete versus one-dimensional polymeric aromatic Möbius cadmium(II) complexes of an N6 tetradentate helical ligand' by Farhad Akbari Afkhami et al., Dalton Trans., 2017, 46, 14888-14896, https://doi.org/10.1039/C7DT02952G.

Halogen bonding in cadmium(II) MOFs: its influence on the structure and on the nitroaldol reaction in aqueous medium.

A solvothermal reaction of Cd(II) with the dicarboxyl-functionalized arylhydrazone pro-ligands, 5-(2-(2,4,6-trioxotetrahydro-pyrimidin-5(2H)-ylidene)hydrazineyl)isophthalic acid (H5L1) and 5-(2-(2,4-dioxopentan-3-ylidene)hydrazineyl)isophthalic acid (H3L2), or their halogen bond donor centre(s) decorated analogs 2,4,6-triiodo-5-(2-(2,4,6-trioxotetrahydropyrimidin-5(2H)-ylidene)hydrazineyl)isophthalic acid (H5L3) and 5-(2-(2,4-dioxopentan-3-ylidene)hydrazineyl)-2,4,6-triiodoisophthalic acid (H3L4), leads to the formation of known [Cd(H3L1)(H2O)2]n (1) and new {[Cd(HL2)(H2O)2(DMF)]·H2O}n (2), [Cd(H3L3)]n (3) and {[Cd2(µ-H2O)2(µ-H2L4)2(H2L4)2]·2H2O}n (4) coordination compounds, respectively. The aggregation of mononuclear units via Cd-OC and Cd-OH2 coordination and CAr-I⋯I types of intramolecular halogen bonds lead to a dinuclear tecton 4. Both CAr-I⋯O and CAr-I⋯I types of intermolecular halogen bonds play a fundamental role in the supramolecular architectures of the obtained metal-organic frameworks 3 and 4. Theoretical (DFT) calculations confirmed the presence of the CAr-I⋯O and CAr-I⋯I halogen bonds in 3 and 4 and allowed their characterisation. The formation of intermolecular noncovalent interactions between the attached iodine substituents to the hydrazone ligands and polar solvent (water or methanol) molecules promoted, at least in part, the solubility of the corresponding complexes (3 and 4), which act as homogeneous catalyst precursors in the Henry reaction between aldehydes and nitroethane. The corresponding ß-nitroalkanol products were obtained in good yields (66-79%) and with good diastereoselectivity (threo/erythro ca. 72 : 28) in water at room temperature.

Resonance Assisted Chalcogen Bonding as a New Synthon in the Design of Dyes.

Intramolecular chalcogen bonding in arylhydrazones of sulfamethizole is strengthened by conjugation in the π-system of a noncovalent five-membered ring. The S⋅⋅⋅O distance in the sulfamethizole moiety of these compounds ranges from 2.698(3) to 2.806(15) Å, which indicates its strong dependence on the attached arylhydrazone fragments. Information on the nature of the intramolecular chalcogen bond was afforded by DFT calculations.

Hoveyda-Grubbs catalysts with an N→Ru coordinate bond in a six-membered ring. Synthesis of stable, industrially scalable, highly efficient ruthenium metathesis catalysts and 2-vinylbenzylamine ligands as their precursors.

A novel and efficient approach to the synthesis of 2-vinylbenzylamines is reported. This involves obtaining 2-vinylbenzylamine ligands from tetrahydroisoquinoline by alkylation and reduction followed by the Hofmann cleavage. The resultant 2-vinylbenzylamines allowed us to obtain new Hoveyda-Grubbs catalysts, which were thoroughly characterised by NMR, ESIMS, and X-ray crystallography. The utility of this chemistry is further demonstrated by the tests of the novel catalysts (up to 10-2 mol %) in different metathesis reactions such as cross metathesis (CM), ring-closing metathesis (RCM) and ring-opening cross metathesis (ROCM).

Hydrogen and halogen bonding in the haloetherification products in chalcone.

Cooperative action of hydrogen and halogen bonding in the reaction of 3-(3,5-di-tert-butyl-4-hydroxyphenyl)-1-phenylprop-2-en-1-one with HCl or HBr in alcohol medium under microwave irradiation (20 W, 80 °C, 10 min) allows the isolation of the haloetherification products (2S,3S)-3-(3-tert-butyl-5-chloro-4-hydroxyphenyl)-2-chloro-3-ethoxy-1-phenylpropan-1-one, C21H24Cl2O3, (2S,3S)-2-bromo-3-(3-tert-butyl-5-bromo-4-hydroxyphenyl)-3-methoxy-1-phenylpropan-1-one, C20H22Br2O3, and (2S,3S)-2-bromo-3-(3-tert-butyl-5-bromo-4-hydroxyphenyl)-3-ethoxy-1-phenylpropan-1-one, C21H24Br2O3, in good yields. Both types of noncovalent interactions, e.g. hydrogen and halogen bonds, are formed to stabilize the obtained products in the solid state.

2-(2-(2,4-dioxopentan-3-ylidene)hydrazineyl)benzonitrile as novel inhibitor of receptor tyrosine kinase and PI3K/AKT/mTOR signaling pathway in glioblastoma.

Nerve growth factor receptor (NGFR), a member of kinase protein, is emerging as an important target for Glioblastoma (GBM) treatment. Overexpression of NGFR is observed in many metastatic cancers including GBM, promoting tumor migration and invasion. Hydrazones have been reported to effectively interact with receptor tyrosine kinases (RTKs). We report herein the synthesis of 23 arylhydrazones of active methylene compounds (AHAMCs) compounds and their anti-proliferative activity against GBM cell lines, LN229 and U87. Compound R234, 2-(2-(2,4-dioxopentan-3-ylidene)hydrazineyl)benzonitrile, was identified as the most active anti-neoplastic compound, with the IC50 value ranging 87 µM - 107 µM. Molecular docking simulations of the synthesized compounds into the active site of tyrosine receptor kinase A (TrkA), demonstrated a strong binding affinity with R234 and concurs well with the obtained biological results. R234 was found to be a negative regulator of PI3K/Akt/mTOR pathway and an enhancer of p53 expression. In addition, R234 treated GBM cells exhibited the downregulation of cyclins, cyclin-dependent kinases and other key molecules involved in cell cycle such as CCNE, E2F, CCND, CDK6, indicating that R234 induces cell cycle arrest at G1/S. R234 also exerted its apoptotic effects independent of caspase3/7 activity, in both cell lines. In U87 cells, R234 induced oxidative effects whereas LN229 cells annulled oxidative stress. The study thus concludes that R234, being a negative modulator of RTKs and cell cycle inhibitor, may represent a novel class of anti-GBM drugs.

Structural versatility of the quasi-aromatic Möbius type zinc(ii)-pseudohalide complexes - experimental and theoretical investigations.

In this contribution we report for the first time fabrication, isolation, structural and theoretical characterization of the quasi-aromatic Möbius complexes [Zn(NCS)2LI] (1), [Zn2(µ1,1-N3)2(LI)2][ZnCl3(MeOH)]2·6MeOH (2) and [Zn(NCS)LII]2[Zn(NCS)4]·MeOH (3), constructed from 1,2-diphenyl-1,2-bis((phenyl(pyridin-2-yl)methylene)hydrazono)ethane (LI) or benzilbis(acetylpyridin-2-yl)methylidenehydrazone (LII), respectively, and ZnCl2 mixed with NH4NCS or NaN3. Structures 1-3 are dictated by both the bulkiness of the organic ligand and the nature of the inorganic counter ion. As evidenced from single crystal X-ray diffraction data species 1 has a neutral discrete heteroleptic mononuclear structure, whereas, complexes 2 and 3 exhibit a salt-like structure. Each structure contains a ZnII atom chelated by one tetradentate twisted ligand LI creating the unusual Möbius type topology. Theoretical investigations based on the EDDB method allowed us to determine that it constitutes the quasi-aromatic Möbius motif where a metal only induces the π-delocalization solely within the ligand part: 2.44|e| in 3, 3.14|e| in 2 and 3.44|e| in 1. It is found, that the degree of quasi-aromatic π-delocalization in the case of zinc species is significantly weaker (by ∼50%) than the corresponding estimations for cadmium systems - it is associated with the Zn-N bonds being more polar than the related Cd-N connections. The ETS-NOCV showed, that the monomers in 1 are bonded primarily through London dispersion forces, whereas long-range electrostatic stabilization is crucial in 2 and 3. A number of non-covalent interactions are additionally identified in the lattices of 1-3.

Correction: Structural versatility of the quasi-aromatic Möbius type zinc(ii)-pseudohalide complexes - experimental and theoretical investigations.

[This corrects the article DOI: 10.1039/C9RA05276C.].

Quasi-aromatic Möbius Metal Chelates.

We report the design as well as structural and spectroscopic characterizations of two new coordination compounds obtained from Cd(NO3)2·4H2O and polydentate ligands, benzilbis(pyridin-2-yl)methylidenehydrazone (LI) and benzilbis(acetylpyridin-2-yl)methylidenehydrazone (LII), in a mixture with two equivalents of NH4NCS in MeOH, namely [Cd(SCN)(NCS)(LI)(MeOH)] (1) and [Cd(NCS)2(LII)(MeOH)] (2). Both LI and LII are bound via two pyridyl-imine units yielding a tetradentate coordination mode giving rise to the 12 π electron chelate ring. It has been determined for the first time (qualitatively and quantitatively), using the EDDB electron population-based method, the HOMA index, and the ETS-NOCV charge and energy decomposition scheme, that the chelate ring containing CdII can be classified as a quasi-aromatic Möbius motif. Notably, using the methyl-containing ligand LII controls the exclusive presence of the NCS- connected with the CdII atom (structure 2), while applying LI allows us to simultaneously coordinate NCS- and SCN- ligands (structure 1). Both systems are stabilized mostly by hydrogen bonding, C-H···π interactions, aromatic π···π stacking, and dihydrogen C-H···H-C bonds. The optical properties have been investigated by diffused reflectance spectroscopy as well as molecular and periodic DFT/TD-DFT calculations. The DFT-based ETS-NOCV analysis as well as periodic calculations led us to conclude that the monomers which constitute the obtained chelates are extremely strongly bonded to each other, and the calculated interaction energies are found to be in the regime of strong covalent connections. Intramolecular van der Waals dispersion forces, due to the large size of LI and LII, appeared to significantly stabilize these systems as well as amplify the aromaticity phenomenon.

Solvent-driven azide-induced mononuclear discrete versus one-dimensional polymeric aromatic Möbius cadmium(ii) complexes of an N6 tetradentate helical ligand.

We report the synthesis and structural characterization of a heteroleptic mononuclear discrete complex [Cd(N3)2(L)(MeOH)]·MeOH (1·MeOH) and a one-dimensional coordination polymer of the composition [Cd3(N3)6(L)]n (2), fabricated from Cd(NO3)2·4H2O and the helical organic ligand benzilbis((pyridin-2-yl)methylidenehydrazone) (L) in the presence of two equivalents of NaN3. The formation of different structures is driven by the solvent. The former complex is formed in the presence of MeOH, while the latter complex is formed in EtOH. The CdII centre in 1·MeOH is trapped by the two pyridyl-imine units of the tetradentate ligand L, two azide ligands and one oxygen atom of one methanol ligand with the CdN6O coordination polyhedron yielding a square face monocapped trigonal prism. The asymmetric unit of 2 consists of three symmetrically independent atoms of CdII, six azide anions and one L. The polymeric structure of 2 is realized through chains of the Cd(N3)2 units which are decorated with Cd(N3)2L units. The CdII atoms from the backbone of the coordination polymer have a distorted octahedral coordination, while the remaining CdII atom forms a trigonal prism with two basal planes nearly parallel to each other. In both complexes, the 12π electron chelate ring of the CdL fragment is shown to be aromatic by establishing it as a Möbius object. Hirshfeld surface analysis of 1 in 1·MeOH and L in 2 showed that the structures of both species are highly dominated by HX (X = H, C and N) contacts, of which the latter two are highly favoured, as well as some contribution from highly enriched CC contacts is clearly observed.

Ligand-Driven Coordination Sphere-Induced Engineering of Hybride Materials Constructed from PbCl2 and Bis-Pyridyl Organic Linkers for Single-Component Light-Emitting Phosphors.

We report design and structural characterization of six new coordination polymers fabricated from PbCl2 and a series of closely related bis-pyridyl ligands LI and HLII-HLVI, namely, [Pb2(LI)Cl4]n, [Pb(HLII)Cl2]n·nMeOH, [Pb(HLIII)Cl2]n·0.5 nMeOH, [Pb2(LIV)Cl3]n, [Pb(HLV)Cl2]n, and [Pb3(LVI)2Cl4]n·nMeOH. The topology of the obtained networks is dictated by the geometry of the organic ligand. The structure of [Pb2(LI)Cl4]n is constructed from the [PbCl2]n two-dimensional (2D) sheets, linked through organic linkers into a three-dimensional framework, which exhibits a unique binodal 4,7-connected three-periodic topology named by us as sda1. Topological analysis of the 2D metal-organic sheet in [Pb(HLII)Cl2]n·nMeOH discloses a binodal 3,4-connected layer topology, regardless of the presence of tetrel bonds. A one-dimensional (1D) coordination polymer [Pb(HLIII)Cl2]n·0.5 nMeOH is considered as a uninodal 2-connected chain. The overall structure of [Pb2(LIV)Cl3]n is constructed from dimeric tetranuclear [Pb4(µ3-LIV-κ6N:N':N″:µ3-O)2(µ4-Cl)(µ2-Cl)2]3+ cationic blocks linked in a zigzag manner through bridging µ2-Cl- ligands, yielding a 1D polymeric chain. Topological analysis of this chain reveals a unique pentanodal 3,4,4,5,6-connected chain topology named by us as sda2. The structure of [Pb(HLV)Cl2]n exhibits a 1D zigzaglike polymeric chain. Two chains are further linked into a 1D gridlike ribbon through the dimeric [Pb2(µ2-Cl)2Cl2] blocks as bridging nodes. With the bulkiest ligand HLVI, a 2D layered coordination polymer [Pb3(LVI)2Cl4]n·nMeOH is formed, which network, considering all tetrel bonds, reveals a unique heptanodal 3,3,3,3,4,5,5-connected layer topology named by us as sda3. Compounds [Pb2(LI)Cl4]n, [Pb2(LIV)Cl3]n, and [Pb(HLV)Cl2]n were found to be emissive in the solid state at ambient temperature. While blue emission of [Pb2(LI)Cl4]n is due to the ligand-centered transitions, bluish-green and white luminescence of [Pb2(LIV)Cl3]n and [Pb(HLV)Cl2]n, respectively, was assigned to ligand-to-metal charge transfer mixed with metal-centered excited states. Molecular as well as periodic calculations were additionally applied to characterize the obtained polymers.

Crystal structure of 1,1-di-acetyl-ferrocene dihydrazone.

The title compound, [Fe(C7H9N2)2], crystallizes with two crystallographically independent mol-ecules in the unit cell. These represent the chiral atropoisomers distinguished by the mutual arrangement of the two acet-yl-hydrazone groups with a cis conformation of the C=N bonds. The two cyclo-penta-dienyl (Cp) rings are planar and nearly parallel, the tilt between the two rings being 3.16 (16)° [4.40 (18)° for the second independent mol-ecule]. The conformation of the Cp rings is close to eclipsed, the twist angle being 0.1 (2)° [3.3 (2)°]. The two acet-yl-hydrazone substituents are also planar and are inclined at 13.99 (15)/9.17 (16)° [6.83 (17)/14.59 (15)°] relative to the Cp rings. The Fe-C bond lengths range from 2.035 (3) to 2.065 (2) Å, with an average of 2.050 (3) Š[2.036 (3) to 2.069 (2), average 2.046 (3) Å], which agrees well with those reported for most ferrocene derivatives. In the crystal, the mol-ecules form dimers via two strong N-H⋯N hydrogen bonds. The dimers are linked into a three-dimensional framework by weak N-H⋯N hydrogen bonds.

Crystal strucutre of rac-methyl (11aR*,12S*,13R*,15aS*,15bS*)-11-oxo-11,11a,12,13-tetra-hydro-9H,15bH-13,15a-ep-oxy-isoindolo[1,2-c]pyrrolo[1,2-a][1,4]benzodiazepine-12-carboxyl-ate.

The title compound, C21H18N2O4, obtained as a racemate, contains a novel heterocyclic system, viz. isoindolo[1,2-c]pyrrolo-[1,2-a][1,4]benzodiazepine. The central diazepane ring has a distorted boat conformation with two phenyl-ene-fused and one methine C atom deviating by 0.931 (1), 0.887 (1) and 0.561 (1) Å, respectively, from the mean plane of the rest of the ring. The γ-lactone ring has an envelope conformation, with the C atom opposite to amide bond deviating by 0.355 (1) Šfrom its plane. In the crystal, mol-ecules form centrosymmetric dimers through pairs of C-H⋯O hydrogen bonds.

[Hexane-2,5-dione bis-(thio-semi-carba-zon-ato)]nickel(II).

In the title compound, [Ni(C8H14N6S2)], the Ni(II) ion is coordinated by N2S2 donor atoms of the tetradentate thio-semicarbazone ligand, and has a slightly distorted square-planar geometry. In the crystal, inversion-related mol-ecules are linked via pairs of N-H⋯N and N-H⋯S hydrogen bonds, forming R 2 (2)(8) ring motifs. Mol-ecules are further linked by slightly weaker N-H⋯N, N-H⋯S and C-H⋯S hydrogen bonds, forming two-dimensional networks which lie parallel to the bc plane.