SHG in a centrosymmetric crystal – can it be possible?

The present report lists selected publications on centrosymmetric com­pounds that manifest second harmonic generation responses in a laser, along with a few publications that dispute the laser outcomes. Two studies provide a plausible explanation for this apparent contradiction between second-order nonlinear susceptibility and inversion symmetry.

Synthesis, structure and magnetocaloric properties of a new two-dimensional gadolinium(III) coordination polymer based on azo­benzene-2,2′,3,3′-tetra­carb­oxy­lic acid

A novel coordination polymer (CP) has been successfully constructed under hydro­thermal conditions via the combination of Gd³⁺ ions and the azo­benzene-2,2′,3,3′-tetra­carb­oxy­lic acid linker. The underlying structural principles com­prise a 1D [Gd₂(COO)₄]_n chain and the linking of neighbouring chains via the organic ligand into a 2D structure with point symbol (4⁴·6²). Further crosslinking into a 3D framework occurs via very short hydrogen bonds. The new CP offers potential for application; magnetic studies reveal that it displays intra­chain anti­ferromagnetic Gd⋯Gd coupling and a cryogenic magnetocaloric effect.

The reaction of thio­urea and 1,3-di­methyl­thio­urea towards organoiodines: oxidative bond formation and halogen bonding

The combination of thio­urea or 1,3-di­methyl­thio­urea with the common halogen-bond donors 1,2-, 1,3-, or 1,4-di­iodo­tetra­fluoro­ben­zene, 1,3,5-tri­fluoro-2,4,6-tri­iodo­ben­zene, and tetra­iodo­ethyl­ene provided several new halogen-bonding cocrystals, as well as three novel reaction products involving the I₂-mediated oxidative formation of new C—S and C—N bonds.

Resolvable polymorphism in an inter­growth of two modifications of tris­(di­ethyl­dithio­carbamato)anti­mony

Tris(di­ethyl­dithio­carbamato)anti­mony(III), [Sb(C₅H₁₀NS₂)₃], is tentatively presumed to com­prise a triclinic and a monoclinic polymorph intergrown into each other. The geometry in the triclinic phase is a ψ-capped octa­hedron and that in the monoclinic phase is a ψ-penta­gonal bipyramid. The study also identifies the polyhedral symbols for a reported pair of polymorphs of another Sb^III coordination com­pound, as well as for those of published polymorphic modifications of other Bi^III and Pb^II coordination com­pounds.

The crystalline forms of nine hydro­chloride salts of substituted tryptamines

The structures of the hydro­chloride salts of nine substituted tryptamines are presented. Substitution at the 1-position changes the nature of the hydro­gen-bonding network.

Synthesis, spectroscopic characterization, structural studies, thermal analysis and mol­ecular docking of N-(2-methyl-5-nitro­phen­yl)-4-(pyridin-2-yl)pyrimidin-2-amine, a precursor for drug design against chronic myeloid leukemia

N-(2-Methyl-5-nitro­phen­yl)-4-(pyridin-2-yl)pyrimidin-2-amine (NPPA), a potential template for drug design against chronic myelogenous leukemia (CML), is reported. X-ray diffraction analysis and a study of the Hirshfeld surfaces revealed important inter­actions between the nitro-group O atoms and the H atoms of the pyridine and pyrimidine rings.

Crystal and mol­ecular structures of some phosphane-substituted cymantrenes [(C₅H₄X)Mn(CO)LL′] (X = H or Cl, L = CO, L′ = PPh₃ or PCy₃, and LL' = Ph₂PCH₂CH₂PPh₂)

The syntheses and structures of the cymantrenes [(C₅H₄X)Mn(CO)LL′] (X = H or Cl; L = CO: L′ = PPh₃ or PCy₃; LL′ = Ph₂PCH₂CH₂PPh₂) are reported. Substitution of CO by phosphanes influences the bond parameters more than replacing the C₅H₅ ligand by C₅H₄Cl.

Synthesis, structure and in vitro biological properties of a new copper(II) com­plex with 4-{[3-(pyri­din-2-yl)-1H-pyrazol-1-yl]meth­yl}benzoic acid

The successful synthesis and structural characterization of a new copper(II) com­plex with the ligand 4-{[3-(pyri­din-2-yl)-1H-pyrazol-1-yl]meth­yl}benzoic acid are described. An investigation of the biological properties of the com­plex indicates strong binding to PTP1B, noncom­petitive inhibition of PTP1B activity and anti­proliferation activity towards MCF7 cell lines.

Influence of chlorine and methyl substituents and their position on the anti­microbial activities and crystal structures of 4-methyl-1,6-di­phenyl­pyrimi­dine-2(1H)-sel­enone derivatives

In a group of 4-methyl-1,6-di­phenyl­py­rimi­dine-2(1H)-sel­en­one derivatives, the influence of the type and position of substituents on anti­microbial activity was studied. Compounds containing a methyl substituent on the py­rimi­dine ring are the most active against bacteria and this activity was not influenced by the position of the group. Similar activity against bacteria is shown by the derivative containing a chlorine substituent in the para position.

Selected solid-state behaviour of three di-tert-butyl-substituted N-salicylideneaniline derivatives: temperature-induced phase transitions and chromic behaviour

Three di-tert-butyl-substituted N-salicylideneaniline derivatives were synthesized, structurally characterized and their chromic properties investigated. Polymorphism was found to affect the photochromic behaviour of the first com­pound, while the second two com­pounds were found to display a temperature-induced phase transition. All of the structures contained an intra­molecular O—H⋯N hydrogen bond.

Methyl β-lactoside [methyl β-D-galacto­pyranosyl-(1→4)-β-D-gluco­pyran­oside] monohydrate: a solvomorphism study

The X-ray crystal structure of methyl β-lactoside [methyl β-D-galacto­pyranosyl-(1→4)-β-D-gluco­pyran­oside] monohydrate was determined and com­pared with the structurally related methyl β-lactoside methanol solvate to evaluate potential structural effects caused by solvomorphism.