Metal Hydrogen-Bonded Organic Frameworks as Open Lewis Acid Catalysts for Two Types of CO2 Transformations.

Efficient and multiple CO2 utilization into high-value-added chemicals holds significant importance in carbon neutrality and industry production. However, most catalysis systems generally exhibit only one type of CO2 transformation with the efficiency to be improved. The restricted abundance of active catalytic sites or an inefficient utilization rate of these sites results in the constraint. Consequently, we designed and constructed two metal hydrogen-bonded organic frameworks (M-HOFs) {[M3(L3-)2(H2O)10]·2H2O}n (M = Co (1), Ni (2); L = 1-(4-carboxyphenyl)-1H-pyrazole-3,5-dicarboxylic acid) in this research. 1 and 2 are well-characterized, and both show excellent stability. The networks connected by multiple hydrogen bonds enhance the structural flexibility and create accessible Lewis acidic sites, promoting interactions between the substrates and catalytic centers. This enhancement facilitates efficient catalysis for two types of CO2 transformations, encompassing both cycloaddition reactions with epoxides and aziridines to afford cyclic carbonates and oxazolidinones. The catalytic activities (TON/TOF) are superior compared with those of most other catalysts. These heterogeneous catalysts still exhibited high performance after being reused several times. Mechanistic studies indicated intense interactions between the metal sites and substrates, demonstrating the reason for efficient catalysis. This marks the first instance on M-HOFs efficiently catalyzing two types of CO2 conversions, finding important significance for catalyst design and CO2 utilization.

From K[ZnBP2O8] to K[(Zn0.5Al0.5)2P2O8]: Substitution-Induced Microporous Zincoaluminophosphate with a Congruent-Melting Behavior.

An open-frame aluminophosphate, K[(Zn0.5Al0.5)2P2O8] (KZAPO), was rationally designed by a substitution design strategy and synthesized by a high-temperature molten salt method. Compared with the parent crystal of K[ZnBP2O8], KZAPO was characterized by similar 4 × 8 × 8 networks, a comparable short-wave ultraviolet transparency and a more regular tetrahedral frame with the mixing of (ZnO4)6- and (AlO4)5- anionic groups, highlighting the multifunctional roles that anionic group mixing played in structural and property modulations. In particular, KZAPO was characterized by a high thermal stability (over 850 °C) and a congruent-melting behavior, being conducive to practical applications.

Stable Lanthanide-Organic Framework as a Luminescent Probe To Detect Both Histidine and Aspartic Acid in Water.

A three-dimensional metal-organic framework (MOF) {[Eu(L)(H2O)2]·DMF} n (1) (H3L = 2'-nitro-3,4',5-biphenyl tricarboxylic acid) was obtained by hydrothermal methods and was characterized in detail. Compound 1 contains [Eu2] binuclear units, and [Eu2] units are further linked by H3L, forming a three-dimensional structure. Stability tests suggest that compound 1 exhibits high solvent, pH, and thermal stability. Besides, we also explored the influence of pH values in the luminescence emission of 1 which shows that pH has a negligible effect on the luminescence intensity with the range of pH = 3-11. Importantly, luminescent investigations reveal that 1 can selectively detect aspartic acid or histidine among 14 amino acids with good regenerability in water. Meanwhile, the concentration of aspartic acid can be quantitatively determined. We also discuss the mechanism of luminescence quenching and enhancement in detail. Importantly, this Eu-MOF provides a MOF-based luminescence sensor to detect two amino acids for the first time.

Hydrothermal synthesis and structural characterization of metal-organic frameworks based on new tetradentate ligands.

The hydrothermal reaction of two new tetradentate ligands with different metal salts of cadmium nitrate, zinc chloride, cobalt nitrate and deprotonated terephthalic acid (H2tp), isophthalic acid (H2ip), 4,4'-oxybisbenzoic acid (H2obba) in H2O/DMF or H2O/methanol gave three metal-organic frameworks (MOFs): {[Zn2(L1)(tp)(formate)2]·H2O}n (), {[Cd2(L2)(ip)2]·2H2O}n (), {[Co2(L2)(obba)2]}n () (L1 = 1,2-bis {2,6-bis [(1H-imidazol-1-yl) methyl]-4-methylphenoxy} ethane, L2 = 1,3-bis {2,6-bis [(1H-imidazol-1-yl) methyl]-4-methylphenoxy} propane). The structures of the frameworks are established by single-crystal X-ray diffraction. Compound is a three-dimensional (3D) framework with a 2-fold interpenetrated form, which exhibits a 2-nodal (3,4)-connected fsh-3,4-P21/c net with a {8(3)}2{8(5)·10} topology. Compound has a 2-nodal (4,8)-connected 3D framework where the dinuclear cadmium cluster secondary building units (SBUs) assemble with isophthalate and ligand L2 to construct a rare topological type sqc22 net with a {3(2)·5(4)}{3(4)·4(4)·5(10)·6(10)} topology. Whereas, Compound can be extended to a 2D interlocked (4,4)-connected 4,4 L28 net with the point symbol {4·6(4)·8}2{4(2)·6(4)}. L1 and L2 are tetradentate ligands with diverse linkers and display different coordination modes. In addition, the thermal stability and photochemical properties of the frameworks are also investigated.

3-[(8-But-oxy-quinolin-2-yl)meth-yl]-1-(pyridin-2-ylmeth-yl)-1H-imidazol-3-ium hexa-fluoridophosphate.

In the cation of the title compound, C(23)H(25)N(4)O(+)·PF(6) (-), the imidazolium ring make dihedral angles of 87.20 (6) and 79.89 (5)° with the pyridine ring and the quinoline system, respectively. In the crystal, C-H⋯F and C-H⋯N hydrogen bonds are observed.

1-[3-(Anthracen-9-yl)-5-(pyridin-2-yl)-4,5-dihydro-1H-pyrazol-1-yl]ethanone.

In the title compound, C(24)H(19)N(3)O, the pyrazoline ring adopts an envelope conformation with the C atom linking to the pyridine ring as the flap. The mean plane of the pyrazoline ring makes dihedral angles of 85.54 (4) and 81.66 (3)° with the pyridine ring and the anthracene ring system, respectively. In the crystal, mol-ecules are linked by C-H⋯O hydrogen bonds. In addition, weak π-π inter-actions [centroid-centroid distances = 3.695 (3)-3.850 (7) Å] are observed.

Bis[1-benzyl-3-(4-methyl-phen-yl)imidazol-2-yl-idene]silver(I) hexa-fluorido-phosphate.

The title silver N-heterocyclic carbene compound, [Ag(C(17)H(16)N(2))(2)]PF(6), crystallizes as a mononuclear salt. The two imidazole rings, which are almost coplanar [maximum deviation from the least squares plane of 0.05 (2) Å], are linked by the Ag atom with a C-Ag-C angle of 178.60 (9)°. In the crystal, C-H⋯F hydrogen bonds, weak π-π inter-actions [centroid-centroid distances = 3.921 (1) and 3.813 (3) Å] and C-H⋯π inter-actions lead to a supermolecular structure.

1-{2-[2-(1H-Benzimidazol-1-yl)eth-oxy]eth-yl}-1H-benzimidazol-3-ium hexa-fluoro-phosphate.

In the title salt, C(18)H(19)N(4)O(+)·PF(6) (-), the dihedral angle between the benzimidazolium and benzimidazole ring systems is 16.24 (2)°. In the cation, a π-π inter-action is observed between the imidazolium ring and the benzene ring of the benzimidazole ring system [centroid-centroid distance = 3.5713 (11) Å]. The PF(6) (-) ion is disordered over two sites, with occupancies of 0.895 (2) and 0.105 (2). In the crystal structure, pairs of N-H⋯N hydrogen bonds link the cations, forming centrosymmetric dimers. The dimers are linked via π-π inter-actions [centroid-centroid distance = 3.5606 (11) Å]. In addition, C-H⋯F hydrogen bonds are observed.

N,N'-Bis(4-nitro-phen-yl)biphenyl-2,2'-dicarboxamide.

In the title compound, C(26)H(18)N(4)O(6), the amide units are approximately coplanar with the benzene ring bonded to the N atom [dihedral angles of 10.59 (10) and 24.00 (12)°], but twisted significantly out of the plane of the benzene ring bonded to the carbonyl C atom [dihedral angles of 57.82 (9) and 58.05 (9)°]. The dihedral angle between the two rings of the biphenyl unit is 77.66 (4)°. Intra-molecular N-H⋯O hydrogen bonds and weak C-H⋯O inter-actions occur. The crystal structure is stabilized by inter-molecular N-H⋯O hydrogen bonds and C-H⋯O contacts.

Diacetonitrile-(3-{2-[8-(2-bromo-eth-oxy)-9,10-dioxoanthracen-1-yl-oxy]eth-yl}-1-(2-pyridyl-meth-yl)imidazolium)silver(I) bis-(hexa-fluorido-phosphate).

The title compound, [Ag(C(27)H(23)BrN(3)O(4))(CH(3)CN)(2)](PF(6))(2), is a mononuclear salt species in which the silver(I) atom is coordinated by one ligand and two acetonitrile mol-ecules and exhibits a distorted T-shaped coordination. The asymmetric unit contains one independent cation and two independent hexa-fluorido-phosphate anions, one of which is disordered over two positions in a 0.756 (11):0.244 (11) ratio. Weak π-π inter-actions between the anthraquinone ring systems [centroid-centroid distance = 3.676 (3) Å], inter-molecular Ag-π inter-actions [Cg⋯Ag = 3.405 Å] and C-H⋯π inter-actions between pairs of adjacent mol-ecules are observed.

3,3'-Dimethyl-1,1'-(methyl-enedi-p-phenyl-ene)diimidazolium bis-(hexa-fluoro-phosphate).

The title N-heterocyclic carbene compound, C(21)H(22)N(4) (2+)·2PF(6) (-), crystallizes as an inversion twin. There are two independent N-heterocyclic carbene dications (A and B) and four independent hexa-fluoro-phosphate anions in the asymmetric unit. The cations are L-shaped with the benzene rings being inclined to one another by 88.82 (16)° in cation A and 87.03 (16)° in cation B. The imidazole rings make dihedral angles of 35.7 (2) and 32.83 (18)° with the attached benzene rings in cation A, and 30.14 (19) and 31.96 (18)° in cation B. In the crystal, the cations are linked via C-H⋯F hydrogen bonds, forming a three-dimensional network. π-π inter-actions involving the benzene and imidazole rings [centroid-centroid distances = 3.602 (2) and 3.723 (2) Å] and C-H⋯π inter-actions are also present.

9-Benzamido-acridinium chloride.

In the title compound, C(20)H(15)N(2)O(+)·Cl(-), the dihedral angle between the fused-ring system and the benzene ring is 63.10 (7)°. In the crystal, N-H⋯Cl hydrogen bonds link the components and aromatic π-π stacking [shortest centroid-centroid distance = 3.6421 (12) Å] occurs.

2-[1-(9-Anthrylmeth-yl)-1H-pyrazol-3-yl]pyridine.

The title compound, C(23)H(17)N(3), can be used in coordination chemistry. The anthracene ring makes dihedral angles of 86.08 (5) and 76.63 (6)°, respectively, with the pyridine and pyrazole rings. The dihedral angle between the pyrazole and pyrimidine rings is 11.79 (7)°. In the structure, weak inter-molecular C-H⋯N hydrogen bonds are observed.

3-Anilino-N-p-tolyl-benzamide.

The title compound, C(20)H(18)N(2)O, which crystallizes with two independent mol-ecules (A and B) in the asymmetric unit, is composed of three aromatic rings (I, II and III). The conformation of the two independent mol-ecules is slightly different. The dihedral angles between the central aromatic ring II and rings I and III are 47.13 (9) and 89.36 (9)°, respectively, for mol-ecule A, and 29.60 (9) and 70.72 (9)°, respectively, for mol-ecule B. Rings I and III are inclined to one another by 86.57 (9)° in mol-ecule A, and 64.59 (10)° in mol-ecule B. The mol-ecular structures are stabilized by intra-molecular N-H⋯O hydrogen bonds. In the crystal structure, mol-ecules are linked through inter-molecular N-H⋯O hydrogen bonds, forming chains propagating in the [010] direction. In addition, a number of C-H⋯π inter-actions are observed.

3-(9-Anthrylmethyl)-1-benzylperimi-dinium hexa-fluoro-phosphate.

In the title compound, C(33)H(25)N(2) (+)·PF(6) (-), the naphthalene ring system is twisted with respect to the anthracene and benzene rings, making dihedral angles of 72.40 (3) and 71.39 (4)°, respectively. The crystal structure is stabilized by intermolecular C-H⋯F hydrogen bonding. Four F atoms of the hexa-fluoro-phosphate anion are disordered over two sets of sites in a 0.645 (4):0.355 (4) ratio.

N-Phenyl-anthranilic anhydride.

The complete mol-ecule of the title compound, C(26)H(20)N(2)O(3), is generated by crystallographic twofold symmetry, with the central O atom lying on the rotation axis. The conformation is stabilized by an intra-molecular N-H⋯O hydrogen bond. The dihedral angle between the inner and outer aromatic ring planes is 61.12 (5)°.

2-Anilino-N-methyl-N-phenyl-benzamide.

The title compound, C(20)H(18)N(2)O, is composed of three aromatic rings, the dihedral angles between the phenyl and benzamide rings, and between the benzamide and aniline rings being 59.86 (9) and 46.57 (10)°, respectively. The mol-ecular structure is stabilized by an intra-molecular N-H⋯O hydrogen bond involving the amino H atom and the benzamide carbonyl O atom. In the crystal structure, C-H⋯O and C-H⋯π inter-actions are present.

N-(2-Amino-phen-yl)-2-anilinobenzamide.

In the title compound, C(19)H(17)N(3)O, the planes of the aromatic substituents attached to the benzamide moiety are almost perpendicular to one another, making a dihedral angle of 88.16 (7)°. The observed conformation of the mol-ecule is produced by an intra-molecular N-H⋯O hydrogen bond.

Bis(3-bromo-methyl-2-meth-oxy-1-naphth-yl)methane.

The title compound, C(25)H(22)Br(2)O(2), crystallizes with two mol-ecules in the asymmetric unit. In each independent mol-ecule, the two naphthalene ring systems are nearly perpendicular to one another, with dihedral angles of 85.6 (1) and 86.2 (1)°. The crystal structure is stabilized by C-H⋯π inter-actions, and inter- and intra-molecular C-H⋯O and C-H⋯Br hydrogen bonds.

N,N'-Bis(2-methoxy-phen-yl)biphenyl-2,2'-dicarboxamide.

In the title compound, C(28)H(24)N(2)O(4), the dihedral angle between the two rings of the biphenyl unit is 75.34 (9)°. The outer aromatic rings form dihedral angles of 66.96 (1) and 85.69 (8)° with the rings to which they are attached . The mol-ecular structure is stabilized by intra-molecular C-H⋯O and N-H⋯O hydrogen bonds. In the crystal structure, inter-molecular N-H⋯O inter-actions are observed.