Functionalized [3 + 3]cycloalkynes: substituent effect on self-aggregation by nonplanar pi-pi interactions

[reaction: see text] Optically active (M)-2,11-dihydroxy-1,12-dimethylbenzo[c]phenanthrene-5,8-dicarbonitrile was synthesized from (M)-1,12-dimethyl-2,11-dinitrobenzo[c]phenanthrene-5,8-dicarbonitrile by the reduction and hydroxylation of nitro groups. The compound was converted to several oxygen-functionalized [3 + 3]cycloalkynes with -OH, -OSiMe2-t-Bu, -OAc, -OTf, or -ONf groups, which are chiral arylene ethynylene macrocycles containing three helicenes. The aggregation behaviors of these [3 + 3]cycloalkynes were examined in CHCl3, THF, and acetone using 1H NMR, CD, and vapor pressure osmometry (VPO) studies and were compared with that of the parent [3 + 3]cycloalkyne. An increasing strength of aggregation in CHCl3 was observed in the following order of the substituted derivatives: -H > -ONf > -OTf > -OAc > -OSiMe2-t-Bu. In THF the following strength of aggregation was observed: -OTf > -ONf > -OAc > -H > -OSiMe(2)-t-Bu > -OH. The aggregation of the functionalized [3 + 3]cycloalkynes is stronger for the compounds with electron-withdrawing substituents than for those with electron-donating substituents. (M)-1,12-dimethylbenzo[c]phenanthrene-2,5,8,11-tetraol was also synthesized from the same intermediate. This electron-rich helicene was readily oxidized to 5,6-quinone in air, and the quinone was suggested to form a self-charge-transfer complex in solid state.     

36-W diode-pumped continuous-wave 1319-nm Nd:YAG ceramic laser

Continuous-wave output at 1319 nm was obtained from a laser-diode-pumped 1% ceramic Nd:YAG laser. As much as 36.3-W output was obtained under pump power of 290 W, with an optical-to-optical conversion efficiency of 12.5%.     

Further asymptotic formulas for the non-null distributions of three statistics for multivariate linear hypothesis

Summary New asymptotic expansions of the non-null distributions of the likelihood ratio, Hotelling's and Pillai's statistics for multivariate linear hypothesis are given in terms of normal distribution function and its derivatives, assuming the matrix of noncentrality parameters is of the same order as the sample size.     

Synthesis and liquid-crystalline properties of thermotropic polyamides containing flexible rodlike units and aliphatic spacers

New polyamides with high molecular weights consisting of flexible rod-like mesogenic units (4,4'-diphenyl and 3,4'-diphenyl moieties having bent linkages in the central parts) and aliphatic spacers were synthesized and the thermotropic liquid-crystalline properties were investigated. Differential scanning calorimetry, texture observations by polarizing microscopy, miscibility tests and X-ray analysis suggested that the polymers showed well-defined thermotropic smectic mesophases. The polyamides containing 4,4'-diphenyl moieties had higher transition temperatures and formed more stable liquid-crystalline phases than the polyamide composed of the 3,4'-diphenyl unit with a kinked bond.