Structures, Photoluminescence, and Reversible Vapoluminescence Properties of Neutral Platinum(II) Complexes Containing Extended π-Conjugated Cyclometalated Ligands

Reacting K2PtCl4 with the tridentate R-C∧N∧C-H2 ligands 2,6-di-(2‘-naphthyl)-4-R-pyridine (R =
H, 1a; Ph, 1b; 4-BrC6H4, 1c; 3,5-F2C6H3, 1d) in glacial acetic acid, followed by heating in dimethyl sulfoxide
(DMSO), gave complexes [(R-C∧N∧C)Pt(DMSO)] (2a−d). In the crystal structures of 2a−c, the molecules
are paired in a head-to-tail orientation with Pt···Pt separations >6.3 Å, and there are extensive close C−H···π
(d = 2.656−2.891 Å), π···π (d = 3.322−3.399 Å), and C−H···OS (d = 2.265−2.643 Å) contacts. [(Ph-C∧N∧C)Pt(PPh3)] (3) was prepared by reacting 2b with PPh3. Reactions of 2a−d with bis(diphenylphosphino)methane (dppm) gave [(R-C∧N∧C)2Pt2(μ-dppm)] (4a−d). Both head-to-head (syn) and head-to-tail (anti)
conformations were found for 4a·6CHCl3·C5H12, whereas only one conformation was observed for 4b·2CHCl3 (syn), 4c·3CH2Cl2 (syn), and 4d·2CHCl3 (anti). In the crystal structures of 4a−d, there are close
intramolecular Pt···Pt contacts of 3.272−3.441 Å in the syn conformers, and long intramolecular Pt···Pt
separations of 5.681−5.714 Å in the anti conformers. There are weak C−H···X (d = 2.497−3.134 Å) and
X···X (X = Cl or Br; d = 2.973−3.655 Å) interactions between molecules 4a−d and occluded CHCl3/CH2Cl2 molecules, and their solvent channels are of varying diameters (∼9−28 Å). Complexes 2a−d, 3,
and 4a−d are photoluminescent in the solid state, with emission maxima at 602−643 nm. Upon exposure
to volatile organic compounds, 4a shows a fast and reversible vapoluminescent response, which is most
intense with volatile halogenated solvents (except CCl4). Powder X-ray diffraction analysis of desolvated
4a revealed a more condensed molecular packing of syn and anti complexes than crystal 4a·6CHCl3·C5H12.

将四氯合铂(II)酸钾（K2PtCl4）与三齿R-C∧N∧C-H2型配体2,6-二(2'-萘基)-4-R-吡啶（R = H，1a；Ph，1b；4-BrC6H4，1c；3,5-F2C6H3，1d）在冰乙酸中反应，随后于二甲基亚砜（dimethyl sulfoxide, DMSO）中加热，得到配合物[(R-C∧N∧C)Pt(DMSO)]（2a−d）。在2a−c的晶体结构中，分子以头-尾取向成对堆叠，Pt···Pt间距大于6.3 Å，且存在大量近距离的C−H···π（键长d=2.656−2.891 Å）、π···π（d=3.322−3.399 Å）以及C−H···O=S（d=2.265−2.643 Å）相互作用。[(Ph-C∧N∧C)Pt(PPh3)]（3）可由2b与三苯基膦（triphenylphosphine, PPh3）反应制得。2a−d与双(二苯基膦)甲烷（bis(diphenylphosphino)methane, dppm）发生反应，得到配合物[(R-C∧N∧C)2Pt2(μ-dppm)]（4a−d）。对于4a·6CHCl3·C5H12，可同时观测到头对头（syn，顺式）与头-尾（anti，反式）两种构象；而4b·2CHCl3（syn）、4c·3CH2Cl2（syn）与4d·2CHCl3（anti）仅存在单一构象。在4a−d的晶体结构中，顺式构象体存在分子内近距离Pt···Pt接触（间距为3.272−3.441 Å），反式构象体的分子内Pt···Pt间距则较长，为5.681−5.714 Å。分子4a−d与包合的CHCl3/CH2Cl2溶剂分子之间存在弱的C−H···X（d=2.497−3.134 Å）及X···X（X=Cl或Br；d=2.973−3.655 Å）相互作用，其溶剂通道直径范围约为9−28 Å。配合物2a−d、3及4a−d在固态下均具有光致发光特性，发射峰最大值位于602−643 nm。当暴露于挥发性有机化合物时，4a表现出快速且可逆的蒸气致发光响应，其中以卤代挥发性溶剂（四氯化碳除外）的响应强度最高。对脱溶剂化的4a进行粉末X射线衍射分析，结果显示其分子堆积相较于晶体4a·6CHCl3·C5H12更为紧密。