Exploring “Triazole-Thiourea” Based Ligands for the Self-Assembly of Photoluminescent Hg(II) Coordination Compounds
作者:Houria Benaissa、Nayarassery N. Adarsh、Koen Robeyns、Jakub J. Zakrzewski、Szymon Chorazy、James G. M. Hooper、Filip Sagan、Mariusz P. Mitoraj、Mariusz Wolff、Smaail Radi、Yann Garcia
DOI:10.1021/acs.cgd.1c00352
日期:2021.6.2
This study represents the first explorative investigation on the supramolecular structural diversity in Hg(II) coordination chemistry with triazole-thiourea ligands leading to a variety of mononuclear, binuclear, and coordination polymers: [Hg(L1)2(L1–)2]} (1), [Hg2(L1)2(μ2-I)2I2]·DMSO} (2), [Hg(L2)(μ2-I)I]·MeOH}∝ (3), [Hg2(μ-L3–)4]}∝ (4), [HgCl(L4–)L4]·MeOH} (5), [Hg2(L4)2(μ2-I)2(I)2]·2MeOH} (6), [Hg2(μ2-L5–)4]}∝ (7), [Hg2(μ2-Cl)2(L6–)2(L6)2]} (8), [Hg2(μ2-Br)2(L6–)2(L6)2]} (9), and [Hg2(μ2-I)2(L6–)2(L6)2]} (10). A reaction mechanism was suggested for the unexpected ligand rearrangement occurring in [Hg2I3(μ3-L5′)]}∝ (11). The ligands were fully characterized including by X-ray crystallography and computational means. This includes six new triazole-thiourea based ligands, namely, 1-R-3-(4H-1,2,4-triazol-4-yl)thiourea (where R = methyl (L1), ethyl (L2), propyl (L3), isopropyl (L4), and its polymorph (L4-poly), allyl (L5), ethyl acetate (L6), and its solvate (L6_MeOH)). Under UV light excitation, 7, 10, and 11 exhibit visible photoluminescence of wide origin, ranging from ligand-centered (LC) fluorescence combined with organic-ligand-to-metal charge transfer (LMCT) emissive states in 7 and 10, up to halide-to-metal charge transfer (XMCT) combined with halide-to-ligand charge transfer (XLCT) emissive states in 11. The variable emission mechanisms in the obtained coordination polymers were elucidated by experimental proofs confronted with theoretical calculations of the electronic densities of states, proving that Hg(II) halide coordination polymers involving flexible 1,2,4-triazole-based ligands form a promising class of luminescent molecular materials.
本研究首次探索了Hg(II)配合物中三唑-硫脲配体的超分子结构多样性,生成了一系列单核、双核和配位聚合物: [Hg(L1)2(L1–)2]} (1), [Hg2(L1)2(μ2-I)2I2]·DMSO} (2), [Hg(L2)(μ2-I)I]·MeOH}∝ (3), [Hg2(μ-L3–)4]}∝ (4), [HgCl(L4–)L4]·MeOH} (5), [Hg2(L4)2(μ2-I)2(I)2]·2MeOH} (6), [Hg2(μ2-L5–)4]}∝ (7), [Hg2(μ2-Cl)2(L6–)2(L6)2]} (8), [Hg2(μ2-Br)2(L6–)2(L6)2]} (9), 和 [Hg2(μ2-I)2(L6–)2(L6)2]} (10)。提出了反应机制,解释了 [Hg2I3(μ3-L5′)]}∝ (11) 中意外的配体重排现象。配体通过X射线晶体学和计算方法得到了充分表征。包括六个新的三唑-硫脲基配体,即1-R-3-(4H-1,2,4-三唑-4-基)硫脲(其中 R = 甲基 (L1), 乙基 (L2), 丙基 (L3), 异丙基 (L4) 及其多晶型物 (L4-poly), 烯丙基 (L5), 乙酸乙酯 (L6), 及其溶剂化物 (L6_MeOH))。在紫外光激发下,7, 10 和 11 显示出可见的宽范围光致发光,从7和10中的配体中心(LC)荧光与有机配体至金属电荷转移(LMCT)发射态,到11中的卤素至金属电荷转移(XMCT)与卤素至配体电荷转移(XLCT)发射态。通过实验证据与态密度的理论计算对比,阐明了所得配位聚合物中可变的发光机制,证明涉及柔性1,2,4-三唑基配体的Hg(II)卤素配位聚合物是一类有前景的发光分子材料。