Assembly of 1D, 2D and 3D lanthanum(iii) coordination polymers with perchlorinated benzenedicarboxylates: positional isomeric effect, structural transformation and ring-opening polymerisation of glycolide.

Utilizing a series of positional isomers of tetrachlorinated benzenedicarboxylic acid ligands, seven La(iii)-based coordination polymers were solvothermally synthesized and structurally characterized. Their structural dimensionalities varying from 1D double chains, to the 2D 3,4,5-connected network, to 3D 6-connected pcu topological nets are only governed by the positions of carboxyl groups on the tetrachlorinated benzene ring. A comprehensive analysis and comparison reveals that the size of the carbonyl solvent molecules (DMF, DEF, DMA, and NMP) can affect the coordination geometries around the La(iii) ions, the coordination modes of carboxylate groups, the packing arrangements, and the void volumes of the overall crystal lattices. One as-synthesized framework further shows an unprecedented structural transformation from a 3D 6-connected network to a 3D 4,5-connected net through the dissolution and reformation pathway in water, suggesting that these easily hydrolyzed lanthanide complexes may serve as precursors to produce new high-dimensional frameworks. The bulk solvent-free melt polymerisation of glycolide utilizing these La(iii) complexes as initiators has been reported herein for the first time. All complexes were found to promote the polymerization of glycolide over a temperature range of 200 to 220 °C, producing poly(glycolic acid) (PGA) with a molecular weight up to 93,280. Under the same experimental conditions, the different catalytic activities for these complexes may result from their structural discrepancy.

10-(3,5-Dinitro-phen-yl)-5,5-difluoro-1,3,7,9-tetra-methyl-5H-dipyrrolo-[1,2-c:2',1'-f][1,3,2]diaza-borinin-4-ium-5-uide.

In an effort to discover new potential boron-dipyrromethene (BODIPY) dyes, the title compound, C19H17BF2N4O4, was prepared from 2,4-dimethyl-pyrrole, 3,5-dinitro-benzaldehyde and boron trifluoride in a one-pot reaction. The BODIPY fragment is nearly planar, with a maximum deviation from the least-squares plane of 0.251 (2) Å, and the benzene ring is inclined at a dihedral angle of 86.8 (6)° to the BODIPY mean plane. In the crystal, pairs of C-H⋯F hydrogen bonds connect neighbouring mol-ecules into inversion dimers, which are linked by further strong C-H⋯F inter-actions, forming a supra-molecular layered array parallel to the bc plane.

{2-[(3,5-Dimethyl-2H-pyrrol-2-yl-idene-κN)(4-nitro-phen-yl)meth-yl]-3,5-dimethyl-1H-pyrrol-1-ido-κN}difluoridoboron.

In an effort to discover novel and potential boron-dipyrromethene (BODIPY) dyes, the title compound, C(19)H(18)BF(2)N(3)O(2), was prepared from 2,4-dimethyl-pyrrole, 4-nitro-benzaldehyde and BF(3)·Et(2)O in a one-pot reaction. There are two independent mol-ecules, A and B, in the asymmetric unit in which the dihedral angles between the benzene ring and boron-dipyrromethene mean plane have significantly different values [82.71 (8)° for mol-ecule A and 73.16 (8)° for mol-ecule B]. Inter-molecular C-H⋯π inter-actions help to stabilize the crystal structure.