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.

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.

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.

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).

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 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.

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.

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.

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.

[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.

2-[2-(4-Meth-oxy-phen-yl)-4,5-diphenyl-1H-imidazol-1-yl]ethanol.

In the title compound, C24H22N2O2, the central imidazole ring makes dihedral angles of 49.45 (8), 88.94 (9) and 19.43 (8)° with the benzene ring and the two phenyl rings, respectively. The dihedral angle between the phenyl rings is 77.86 (9)°, and they form dihedral angles of 49.06 (9) and 67.31 (8)° with the benzene ring. In the crystal, mol-ecules are linked by O-H⋯N hydrogen bonds, forming chains along the b axis. These chains are connected by C-H⋯O hydrogen bonds, forming a two-dimensional network parallel to (100). In addition, C-H⋯π inter-actions are also observed. The terminal C and O atoms of the ethanol group are disordered over two sets of sites with an occupancy ratio of 0.801 (5):0.199 (5).

Ethyl 4-(5-bromo-2-hy-droxy-phen-yl)-2,7,7-trimethyl-5-oxo-1,4,5,6,7,8-hexa-hydro-quinoline-3-carboxyl-ate.

In the title compound, C21H24BrNO4, the dihedral angle between the heterocyclic ring and the pendant aromatic ring is 80.20 (13)°. The hexahydroquinone [i.e. the one with the C=O group] ring adopts a sofa conformation. An intra-molecular O-H⋯O hydrogen bond generates an S(6) ring motif. The ethyl group is disordered over two sets of sites with a refined site occupancy ratio of 0.633 (10):0.366 (10). In the crystal, mol-ecules are linked by N-H⋯O inter-actions, forming chains parallel to [101]. There are no significant C-H⋯π or π-π inter-actions in the crystal structure.

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.

9-(2-Hy-droxy-4,4-dimethyl-6-oxocyclo-hex-1-en-1-yl)-3,3-dimethyl-2,3,4,9-tetra-hydro-1H-xanthen-1-one.

The cyclo-hexene ring that constitutes a part of the tetra-hydroxanthene fused-ring system of the title compound, C(23)H(26)O(4), adopts a flattened half-chair conformation that approximates an envelope conformation (in which the methyl-ene C atom bearing the two methyl substituents represents the flap) as five of the six atoms lie approximately on a plane (r.m.s. deviation = 0.020 Å). The mean plane of the cyclo-hexene ring with the hy-droxy substituent is approximately perpendicular to the mean plane of the tetra-hydroxanthene system. In the crystal, adjacent mol-ecules are linked by O-H⋯O(carbon-yl) hydrogen bonds into a chain running along the b axis.

Diaqua-bis-(N,N-diethyl-pyridine-3-carboxamide-κN)bis-{4-[2-(2,4-dioxopentan-3-yl-idene)hydrazin-1-yl]benzoato-κO}copper(II).

In the title compound, [Cu(C(12)H(11)N(2)O(4))(2)(C(10)H(14)N(2)O)(2)(H(2)O)(2)], the Cu(II) atom lies on a center of inversion and is coordinated by carboxyl-ate O atoms, pyridine N atoms and two water mol-ecules in an elongated octa-hedral geometry. The pyridine ring is oriented at a dihedral angle of 74.83 (12)° with respect to the benzene ring. Intra-molecular O-H⋯O and N-H⋯O hydrogen bonding is observed. The water mol-ecule is a hydrogen-bond donor to the carbonyl O atom of an adjacent carboxyl-ate group, generating a chain running along the a axis. One of the ethyl groups is disordered over two sets of sites in a 0.787 (5):0.213 ratio.

catena-Poly[[aqua-bis-{4-[2-(2,4-dioxopentan-3-yl-idene)hydrazin-1-yl]benzo-ato-κO}copper(II)]-µ-N,N-diethyl-pyridine-3-carboxamide-κN:O].

The Cu(II) atom in the title compound, [Cu(C(12)H(11)N(2)O(4))(2)(C(10)H(14)N(2)O)(H(2)O)](n), lies in a square plane defined by the O atoms of the carboxyl-ate ions, the N atom of the N-heterocycle and the water mol-ecule. Coordination by an amido O atom of an adjacent N-heterocycle in the apical direction leads to a polymeric chain running along [01[Formula: see text]]. The chain motif is consolidated by hydrogen bonds involving the water mol-ecule; the water mol-ecule is a hydrogen-bond donor to the free carbonyl atoms of the carboxyl-ate ions. Intra-molecular N-H⋯O hydrogen bonds also occur.

1-(6-Methyl-3-phenyl-2-sulfanyl-idene-1,2,3,4-tetra-hydro-pyrimidin-5-yl)ethanone.

In the title compound, C(13)H(14)N(2)OS, four C atoms of the phenyl ring are disordered over two sets of sites in a 0.60 (3):0.40 (3) ratio. The heterocyclic ring is essentially planar (r.m.s. deviation = 0.017 Å) and forms dihedral angles of 82.0 (2) and 79.3 (3)°, respectively, with the major and minor occupancy components of the phenyl ring. The crystal packing features N-H⋯O hydrogen bonds, which link the mol-ecules into C(6) chains running parallel to the b axis.

Ethyl 2,7,7-trimethyl-5-oxo-4-phenyl-1,4,5,6,7,8-hexa-hydro-quinoline-3-carboxyl-ate.

In the title compound, C(21)H(25)NO(3), the hydro-pyridine ring that constitutes a part of the hexa-hydro-quinoline fused-ring system adopts a sofa conformation; the methine C atom deviates from the least-squares plane defined by the remaining five non-H atoms (r.m.s. deviation = 0.088 Å) by 0.454 (3) Å. The phenyl ring is aligned at 85.5 (1)° with respect to this mean plane. In the crystal, adjacent molecules are linked via an N-H⋯O hydrogen bond, involving the amino group and the carbonyl O atom of the fused-ring system, forming chains running along [100]. The ethyl group is disordered over two positions in a 0.609 (6):0.391 (6) ratio.

2-(4-Meth-oxy-phen-yl)-4,5-diphenyl-1-(prop-2-en-1-yl)-1H-imidazole.

The asymmetric unit of the title compound, C(25)H(22)N(2)O, contains two independent mol-ecules (A and B), with significantly different conformations. In mol-ecule A, the central imidazole ring makes dihedral angles of 88.26 (10) and 12.74 (11)° with the two phenyl rings, and 22.06 (9)° with the benzene ring. In mol-ecule B, one of the phenyl rings is disordered over two sites, each having an occupancy of 0.5. Here the central imidazole ring forms dihedral angles of 79.24 (10)° with the ordered phenyl ring, and 3.5 (5) and 22.6 (5)° with the two parts of the disordered phenyl ring. The dihedral angle involving the benzene ring is 67.49 (10)°. The -N-C(H(2))-C(H)-C(H(2)) torsion angles of the prop-1-ene group in the two mol-ecules are very similar, 0.5 (3) and 1.3 (4)° for mol-ecules A and B, respectively. The crystal structure is stabilized by C-H⋯π inter-actions.