In situ cyclodehydration of iminodiacetic acid into 2,5-diketopiperazine-1,4-diacetate in lanthanide-based coordination polymers

Improved Predictive Tools for Structural Properties of Metal-Organic Frameworks

The accurate determination of structural parameters is necessary to understand the electronic and magnetic properties of metal-organic frameworks (MOFs) and is a first step toward accurate calculations of electronic structure and function for separations and catalysis. Theoretical structural determination of metal-organic frameworks is particularly challenging because they involve ionic, covalent, and noncovalent interactions, which must be treated in a balanced fashion. Here, we apply a diverse group of local exchange-correlation functionals (PBE, PBEsol, PBE-D2, PBE-D3, vdW-DF2, SOGGA, MN15-L, revM06-L, SCAN, and revTPSS) to a broad test set of MOFs to seek the most accurate functionals to study various structural aspects of porous solids, in particular to study lattice constants, unit cell volume, two types of pore size characteristics, bond lengths, bond angles, and torsional angles). The recently developed meta functionals revM06-L and SCAN, without adding any molecular mechanics terms, are able to predict more accurate structures than previously recommended functionals, both those without molecular mechanics terms (PBE, PBEsol, vdW-DF2, and revTPSS) and those with them (PBE-D2 and PBE-D3). To provide a broader test, these two functionals are also tested for lattice constants and band gaps of unary, binary, and ternary semiconductors.

Water stable oxalate-based coordination polymers with in situ generated cyclic dipeptides showing high proton conductivity

Presented here are two water stable oxalate-based coordination polymers with in situ generated cyclic dipeptides, which show high proton conductivities on the order of 10⁻³ S cm⁻¹ at 85 °C under 98% relative humidity.

Two new metal–organic frameworks based on tetrazole–heterocyclic ligands accompanied by in situ ligand formation

Two new MOFs have been constructed by the Dimroth rearrangement of the in situ generated organic ligand 5-((2H-tetrazol-5-yl)amino)isophthalic acid (H₃L).

A series of cobalt and nickel clusters based on thiol-containing ligands accompanied by in situ ligand formation

We report a series of cobalt and nickel clusters based on thiol-containing ligands, 2-mercaptobenzothiazole (HMBT) and 2-mercaptobenzimidazole (H₂MBI), accompanied by in situ ligand transformation of HMBT. The magnetic properties of the cobalt clusters have been investigated.

Experimental, DFT and quantum Monte Carlo studies of a series of peptide-based metal–organic frameworks: synthesis, structures and properties

Properties and the function–structure relation of four peptide-based MOFs were identified by experimental measurements, DFT and quantum Monte Carlo calculation.

Photoluminescent 3D lanthanide-organic frameworks based on 2,5-dioxo-1,4-piperazinylbis(methylphosphonic) acid formed via in situ cyclodehydration of glyphosates

Hydrothermal reactions of lanthanide nitrates with glyphosate have resulted three new isostructural 3D lanthanide-organic frameworks, Ln(NO3)(H2L) [Ln = Eu (1), Tb (2), Gd (3); H4L = 2,5-dioxo-1,4-piperazinylbis(methylphosphonic) acid], with good yields, where H4L as a new ligand was formed via in situ cyclodehydration of original ligand glyphosates during the hydrothermal reaction. The compounds were thoroughly characterized by IR, UV-vis, elemental analysis, single-crystal X-ray diffraction analysis, powder X-ray diffraction analysis, and thermogravimetric/differential thermal analysis (TG-DTA). Three compounds display 3D 6,6-connected open frameworks with 4(13)·6(2) topology possessing 1D channels in which NO3(-) anions act as troglodytes by chelating Ln(3+) centers. The TG-DTA study of the compounds showed remarkable thermal stability up to 380 °C. Under room temperature UV-light irradiation, the Eu(3+) and Tb(3+) compounds showed the corresponding characteristic Ln(3+) intra 4f(n) emission peaks. The triplet energy level (21882 cm(-1)) of the ligand (H4L) was determined from the emission spectrum of its Gd(3+) compound at 77 K. The emission lifetimes (1.54 ms of (5)D0 for compound 1 and 1.98 ms of (5)D4 for compound 2) and absolute emission quantum yields (10.1% for compound 1 and 5.9% for compound 2) were also determined.

A novel La(III)-based metal-organic framework (MOF) with a new topology: poly[diaquabis(μ5-2,5-dioxopiperazine-1,4-diacetato)(μ2-oxalato)dilanthanum(III)]

In the title metal-organic framework (MOF), [La(C(8)H(8)N(2)O(6))(C(2)O(4))(0.5)(H(2)O)](n), the La(III) cation is coordinated by eight O atoms in a square antiprismatic configuration. Each La(III) cation is connected to adjacent La(III) cations by bridging 2,5-dioxopiperazine-1,4-diacetate (PODC(2-)) and oxalate (lying about an inversion centre) ligands, generating two-dimensional grid layers. The layers are further linked via the carboxylate groups of the PODC(2-) ligands in syn-syn and syn-anti modes, resulting in a three-dimensional framework with a short Schläfli vertex notation of {4(7).6(3)}{4(7).6(7).8}.

Ammine(2,2'-bipyridine-kappa(2)N,N')silver(I) nitrate: a dimer formed by pi-pi stacking and ligand-unsupported Ag...Ag interactions

Reaction of AgNO(3) and 2,2'-bipyridine (bipy) under ultrasonic treatment gave the title compound, [Ag(C(10)H(8)N(2))(NH(3))]NO(3). The crystal structure consists of dimers formed by two symmetry-related Ag(I)-bipy monomers connected through intra-dimer pi-pi stacking and ligand-unsupported Ag...Ag interactions. A crystallographic C2 axis passes through the mid-point of and is perpendicular to the Ag...Ag(i)(-x + 1, y, -z + 1/2) axis. In addition, each Ag(I) cation is coordinated by one chelating bipy ligand and one ammine ligand, giving a trigonal coordination environment capped by the symmetry-equivalent Ag atom. Molecules are assembled by Ag...Ag, pi-pi, hydrogen-bond (N-H...O and C-H...O) and weak Ag...pi interactions into a three-dimensional framework. Comparing the products synthesized under different mechanical treatments, we found that reaction conditions have a significant influence on the resulting structures. The luminescence properties of the title compound are also discussed.