The discrete mononuclear [Ni(H₂L)(bpyBr)₂]·2H₂O (1) and one-dimensional [Ni₂(H₂L)₂(bpyBr)₂(H₂O)₃]_n (2) coordination compounds were obtained and characterized (H₄L = 5,5′-(butane-1,4-diylbis(oxy))diisophthalic acid; bpyBr = 4,4′-dibromo-2,2′-bipyridyl). The two compounds can undergo SC–SC transformation into each other in a process stimulated by excess H₄L or bpyBr that involves coordination bond cleavage and formation, which is a very rare case and should be defined as an S_N2 nucleophilic ligand substitution reaction of the coordination compounds. Additionally, the proton conductivities of the Nafion membrane doped by compounds 1 and 2 were studied. Compounds 1 and 2 can enhance the proton conductivity of the composite membrane to about 51.80% and 20.94% higher than that of pure Nafion. It is speculated that the high proton density offered by the uncoordinated protonated carboxylate groups may endow the two compounds with good conductivities. In addition, the better hydrophilicity and stronger acidity of compound 1 deduced from the structure analyses and verified by the water uptake tests and IR spectra may lead to its higher conductivity.

中文翻译：

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在两个Ni（II）配位化合物中配体取代引起的单晶至单晶转变，显示质子电导率随之变化

离散单核[Ni（H ₂ L）（bpyBr）₂ ]·2H ₂ O（1）和一维[Ni ₂（H ₂ L）₂（bpyBr）₂（H ₂ O）₃ ] _n（2）获得并表征了配位化合物（H ₄ L = 5,5'-（丁烷-1,4-二基双（氧基））二间苯二甲酸； bpyBr = 4,4'-二溴-2,2'-联吡啶基）。在过量的H ₄ L或bpyBr刺激下，涉及配位键的裂解和形成，这两种化合物可能会经历SC–SC相互转化，这是非常罕见的情况，应定义为S_N2亲核配体取代反应的配位化合物。此外，还研究了化合物1和2掺杂的Nafion膜的质子电导率。化合物1和2可以使复合膜的质子传导率比纯Nafion提高约51.80％和20.94％。据推测，由未配位的质子化的羧酸酯基团提供的高质子密度可以赋予这两种化合物良好的导电性。另外，由结构分析得出并经吸水试验和IR光谱证实的化合物1的更好的亲水性和更强的酸性可导致其更高的电导率。