Structure and Photoluminescence of a New 3D Cu_4I_4 Hybrid Constructed by a Flexible Acyclic Aliphatic Diamine with Steric Effect

A new 3D copper(I) iodide hybrid, [Cu4I4(TMEDA)2]n(1, TMEDA = N,N,N',N'-tetramethylethylenediamine), has been solvothermally synthesized and characterized by singlecrystal X-ray diffraction, IR spectroscopy, elemental analysis, powder X-ray diffractions and thermogravimetric analysis. Compound 1 crystallizes in tetragonal space group P42/n with a = b = 11.5663(7) A, c = 9.2456(11) A, V = 1236.87(18) A3, Z = 8, C3H8 CuIN, Mr = 248.54, Dc = 3.507 g/cm3, F(000) = 920, μ(MoKα) = 8.388 mm–1, the final R = 0.0244 and wR = 0.0573 for 1118 observed reflections(I 2σ(I)). The hybrid framework is built up from cubane-like Cu4I4 cluster and flexible acyclic aliphatic diamine TMEDA, which can be simplified into a twofold interpenetrating dia network. The solid state luminescence spectrum displays a strong yellow emission band at room temperature(Aex = 340 nm, Aem = 530 nm). Results reveal that steric effect of N-substituted methyl groups in TMEDA have obvious influence on the structure and photoluminescent property of compound 1.     

Ultrafast proton transfer dynamics of 2-(2'-hydroxyphenyl)benzoxazole dye in different solvents

The excited-state intramolecular proton transfer of 2-(2-hydroxyphenyl)benzoxazole dye in different solvents is investigated using ultrafast femtosecond transient absorption spectroscopy combined with quantum chemical calculations.Conformational conversion from the syn-enol configuration to the keto configuration is proposed as the mechanism of excited-state intramolecular proton transfer.The duration of excited-state intramolecular proton transfer is measured to range from 50 fs to 200 fs in different solvents.This time is strongly dependent on the calculated energy gap between the N-S;and T-S;structures in the S;state.Along the proton transfer reaction coordinate,the vibrational relaxation process on the S;state potential surface is observed.The duration of the vibrational relaxation process is determined to be from8.7 ps to 35 ps dependent on the excess vibrational energy.     

带电塑料梳子吸引纸屑的“ 跳变”现象

用头发摩擦过的塑料梳子带有一定量的电荷, 将其靠近细小纸屑, 距离较远时纸屑纹丝不动. 继续移 动梳子, 发现纸屑开始出现略微的颤动. 此时只需将塑料梳子稍作移动, 纸屑便像被施了魔法一样“ 噌”地跳上梳 子, 该过程几乎是在瞬间发生的. 分析得到塑料梳子与纸屑之间吸引力的大小与r 5 成反比, 同两个带电物体之间库 仑力与r 2 成反比相比, 该吸引力更加依赖于二者的距离, 随着距离的减小, 力增加得更快, 因此出现“ 跳变”现象