Lewis Acidic Borane Adducts of Pyridines and Stilbazoles for Nonlinear Optics

Abstract

A series of neutral pyridyl adducts involving the strong Lewis acids BF 3 and B(C 6 F 5 ) 3 has been prepared, and their second-order nonlinear optical coefficients (EFISH method) have been examined. The formation of the pyridyl-boron bond leads to enhancement of the dipole moments and second-order NLO coefficients (β and β(0)). Reactions of DMAP (4-Me 2 N-C 5 H 4 N) with BH 3 , BF 3 , and B(C 6 F 5 ) 3 give the corresponding neutral pyridine adducts DMAP‚-BH 3 (orthorhombic, Pbca, a ) 9.6914(7) Å; b ) 11.7173(9) Å; c ) 22.718(2) Å; V ) 1622.4(5) Å 3 ; Z ) 8; p ) 1.114 g cm -3 ), DMAP‚BF 3 (orthorhombic, Pbca, a ) 10.430(3) Å; b ) 8.111(2) Å; c ) 20.295(7) Å; V ) 1717.0(9) Å 3 ; Z ) 8; p ) 1.470 g cm -3 ), and DMAP‚B(C 6 F 5 ) 3 (orthorhombic, Pbca, a ) 12.322(1) Å; b ) 20.556(2) Å; c ) 28.455(3) Å; V ) 7207.4(14) Å 3 ; Z ) 8; p ) 1.508 g cm -3 ). Reactions of Me 2 N-4-C 6 H 4 -CHdCH-C 5 H 4 N, MeO-4-C 6 H 4 -CHdCH-C 5 H 4 N, and Me 2 N-4-C 6 H 4 -CtC-C 5 H 4 N with BF 3 and B(C 6 F 5 ) 3 result in materials that are highly luminescent and incorporate structural features that are known to give rise to large second-order NLO effects. X-ray diffraction analysis for the compound Me 2 N-4-C 6 H 4 -CtC-C 5 H 4 N‚B(C 6 F 5 ) 3 (monclinic, P2 1 /c, a ) 9.883(2) Å; b ) 10.717(1) Å; c ) 28.421-(4) Å; β ) 91.96(1)°; V ) 2993.4(8) Å 3 ; Z ) 4; p ) 1.629 g cm -3 ) is also described.

A General Synthetic Pathway to Lewis Base-Stabilized, MonomericGroup 13/15 Compounds

“…The proton resonances of the organic ligands bound to the metal centers appear further downfield (MeAl, EtAl, and Me 3 Si resonances) than those of the starting heterocycles, while those of the dmap molecule are shifted upfield. These findings are in agreement with results observed for similar borane adducts, [12] and correspond to a partial rearrangement of the charge distribution within the aromatic ring as shown in Scheme 2. (1) As found in the corresponding monomers of the higher homologues dmapϪAl(R 2 )E(SiMe 3 ) 2 (R ϭ Me, Et, E ϭ Sb, Bi), [3,4] the substituents bonded to Al and the particular pentele atom adopt a staggered conformation relative to are at the lower end of typical EϪSi bond lengths.…”

The Pentaphenylborole–2,6‐Lutidine Adduct: A System with Unusual Thermochromic and Photochromic Properties

“…Remarkably, some of the boranepyridine adducts have interesting nonlinear optical properties. [4] Recently, Wang and co-workers have demonstrated that irradiation of adducts such as A leads to the formation of B, which contains a boracyclopropane ring with the B À N linkage remaining intact (Scheme 1). [5] Analogous rearrangement reactions have been found during photolysis of tetraphenylborates, where the generation of free radical species has also been observed (Scheme 1).…”

Linker Conjugation Effects in Rhenium(I) Bifunctional Hole‐Transport/Emitter Molecules

“…After purification on silica with diethyl ether as an eluent, a yellow powder was obtained which was recrystallised from diethyl ether/hexane mixture to give the product (0.141 g, 31 %). [44] Synthesis of the fac-[Re(CO) 3 (HT)A C H T U N G T R E N N U N G (phen)] complexes: These complexes were prepared based on established literature procedures. [6,16,18,33,45] Commercially obtained [Re(CO) 5 Cl] (Aldrich) and 1,10-phenanthroline·H 2 O (Aldrich) were heated under refluxed in absolute ethanol to give fac-[Re(CO) 3 ClA C H T U N G T R E N N U N G (phen)].…”