Cationic and Betaine-Type Boronated Acridinium Dyes: Synthesis, Characterization, and Photocatalytic Activity.

A series of isomeric boronated acridinium dyes were obtained by reactions of 10-(4'-octyloxyphenyl) functionalized 9(10)-acridanone derivative with lithiated phenylboronic azaesters followed by aromatization with perchloric acid. The effect of the position of boronic group attached at ortho, meta, and para positions of the 9-phenyl ring on the photophysical properties was investigated. Conversion to related betaine trifluoroborato-substituted compounds was successfully performed, and the effect of this structural change on UV-vis absorption and fluorescence spectroscopy characteristics was established.

Crystal structure of (2',3,6'-tri-chloro-biphenyl-2-yl)boronic acid tetra-hydro-furan monosolvate.

The title compound, C12H8BCl3O2·C4H8O, crystallizes as a tetra-hydro-furan monosolvate. The boronic acid group adopts a syn-anti conformation and is significantly twisted along the carbon-boron bond by 69.2 (1)°, due to considerable steric hindrance from the 2',6'-di-chloro-phenyl group that is located ortho to the boronic acid substituent.

Crystal structure of (2-benzyl-oxy-pyrimidin-5-yl)boronic acid.

The boronic acid group in the title compound, C11H11BN2O3, adopts a syn-anti conformation and is almost coplanar with the aromatic rings , making a dihedralangle of 3.8 (2)°. In the crystal, adjacent mol-ecules are linked via pairs of O-H⋯O inter-actions, forming centrosymmetric dimers with an R 2 (2)(8) motif, which have recently been shown to be energetically very favorable (Durka et al.

{2-[(2,6-Difluoro-phen-oxy)meth-yl]phen-yl}boronic acid.

The planes of the two benzene rings in the mol-ecule of the title compound, C(13)H(11)BF(2)O(3), form a dihedral angle of 76.06 (3)°; the C-O-C-C torsion angle characterizing the conformation of the central link of the mol-ecule is -79.20 (1)°.

[3-Bromo-2-(3-fluoro-benz-yloxy)phen-yl]boronic acid.

In the title compound, C(13)H(11)BBrFO(3), the dioxy-boron fragment is close to co-planar with the benzene ring to which the B atom is connected [dihedral angle = 8.96 (4)°]. The dihedral angle between the two benzene rings is 14.

tert-Butyl 2-(dihydroxyboryl)pyrrole-1-carboxylate.

In the title compound, C(9)H(14)BNO(4), the carbonyl and boronic acid groups are essentially coplanar with the pyrrole ring and the boronic acid group has an exo-endo conformation. The exo-oriented OH is engaged in an intra-molecular O-H⋯O inter-action, while the endo-oriented one is involved in inter-molecular hydrogen bonding to form centrosymmetric dimers. A supra-molecular assembly is achieved through inter-actions involving the tert-butyl groups, forming infinite chains along the crystallographic b axis.

2,3-Difluoro-4-formylphenylboronic acid.

The molecule of the title compound, 2,3-F(2)-4-(CHO)C(6)H(2)B(OH)(2) or C(7)H(5)BF(2)O(3), contains a formyl group coplanar with the benzene ring. The boronic acid group is twisted with respect to the benzene ring plane. The molecules are organized into infinite chains via intermolecular O-H.