St(+)-Ipalbidine. [a]~+-.54.1° (c= 1, ethanol) as hydrobromide, was synthesized from natural (Stproline with retention of configuration. The hldrobromide of the synthetic product was identical in all respects with that of the OptiC3lly active natural ipalbidine isolated from the Chinese species Tpomoea fiordwickii Hemsl.Hua Tuo Dou (follow the name of an ancient famous Chinese surg-.on Hua Tuo) are the seeds of Ipomoea hardwickii Hemsl, and have been used in the folk medicine of South China as an analgesic for years, It was interesting that the ipalbidine(1)' isolated therefrom appeared optically active, in contrast to the racemic form from ljmmmz species indigenous to other parts of the world.2h So far, (itipalbidine has been synthesized -by six groups' and resolved to (ftipalbidine, which was used furthsr for the synthesis of naturally occurring (+)-ipalbine (21.93We haw synthesized (Sj(+)-ipaltidine from the optically active natural (S)-proline 3 by reaction illustrated in Scheme 1 with retention of configuration. Scheme 1H 3

Phosphorescent mechanochromic materials may change their luminescence color and intensity with large spectral shifts under a mechanical force stimulus.

We report interesting photomechanical behaviors of the dynamic molecular crystals of (E)-2-(2,4-dichlorostyryl)benzo[d]oxazole (BOACl24). The photosalient effect of the rod-like crystal based on a metal-free olefin driven by photodimerization is observed. Moreover, the needle-like crystals of BOACl24 exhibit a reversible bending away from a UV light source. The nanofibers curl easily under UV irradiation in an organogel, in which the photo-induced rolling of a small slice occurs. This suggests that the rapid release of the accumulated strain during photodimerization may lead to a photosalient effect, and the bending or curling happens when the strain is released slowly. Notably, [2+2] cycloaddition takes place between two different conformational isomers of BOACl24 on account of the rotation of the benzoxazole ring around the C-C bond in an excited state before photodimerization. Such topo-photochemical reaction has not been reported elsewhere.

A new organogelator based on a salicylideneaniline derivative with cholesterol moieties was synthesized, and it was proposed that it could gelate various organic solvents, such as 1-butanol, 1-octanol, butyl acetate, tetrachloromethane, benzene, toluene through combination with a gelation test. From the results of analysis by UV/Vis absorption, circular dichroism (CD), X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) studies and semiempirical (AM1) calculations, we believed that the gelator molecules could self-assemble into left-handed helical nanofibers through unimolecular layer packing, which further twisted into the thicker fibers and constructed 3D networks in the gel phase. Interestingly, the organogel exhibited strong fluorescence enhancement relative to a solution of the same concentration because of the formation of J aggregations. Meanwhile, photochromism of the organogel could take place under UV-light irradiation. Both strong fluorescence emission and photochromism properties were concurrent in one system based on a salicylideneaniline derivative. It was suggested that the self-assembly of the functional organogelator could lead to unique photophysical properties.

A 6-(4-bromophenoxy)hexyl group linked to carbazole gives crystals that exhibit strong white photoluminescence with an efficiency of 72.6%, a Φ P of 39.5%, and a phosphorescence lifetime of 200 ms.

In situ ACQ-to-AIE transformation was achieved by light-induced [2+2] cycloaddition via through-space conjugation.

A new salicylideneaniline-based organogelator has been synthesized, and it can gelatinize organic solvents, including cyclohexane, toluene, benzene, and some mixed solvents. SEM images show that it has self-assembled into 1-D nanofibers, which further cross-link to form 3-D network. On the basis of the results of small-angle XRD and the optimized molecular length by semiempirical quantum calculations, the gelators are supposed to pack into a unimolecular lamellar structure with a period of 3.01 nm. Significantly, reversible chromism is realized with respect of the tautomerism between the NH and OH forms during the sol-gel freezing repetition. Furthermore, the gel can emit intense green light, and the fluorescent quantum yield of the gel is approximately 600 times higher than that of the solution. The aggregation-induced emission enhancement is ascribed to the formation of J aggregation and the inhibition of intramolecular rotation in the gel state.

4-(Carbazol-9-yl)benzaldehyde could emit yellow RTP, which could last for 3 s because of efficient intersystem crossing. Moreover, multicolor luminescent switches could be realized by simply applying a mechanical force stimulus.