Cheadle Carl, Ratcliff Jessica, Berezin Mikhail, Pal'shin Vadim, Nemykin Victor N, Gerasimchuk Nikolay N
Department of Chemistry, Temple Hall 431, Missouri State University, Springfield, MO 65897, USA.
Dalton Trans. 2017 Oct 10;46(39):13562-13581. doi: 10.1039/c7dt02317k.
Several complexes of "PtL" composition containing two cyanoxime anions - 2-oximino-2-cyano-N-piperidineacetamide (PiPCO) and 2-oximino-2-cyano-N-morpholylacetamide (MCO) - have been obtained and characterized both in solution and in the solid state. Complexes exist as two distinct polymorphs: monomeric yellow complexes and dark-green [PtL] 1D polymers, while for the MCO anion a red, solvent containing dimeric [Pt(MCO)·DMSO] complex has also been isolated. The interconversion of polymorphs was investigated. The monomeric PtL units are arranged into anisotropic extended solid [PtL] polymers with the help of PtPt metallophilic interactions. Crystal structures of monomeric PtL (L = PiPCO, MCO) and red dimeric [Pt(MCO)·DMSO] complexes were determined and revealed the cis-arrangement of cyanoxime anions. The Pt-Pt distance in the "head-to-tail" red dimer was found to be 3.133 Å. The structure of the polymeric [Pt(PiPCO)] compound was elucidated using the EXAFS method and evidenced the formation of Pt-wires with ∼3.15 Å intermetallic separation. The EPR spectra of both 1D polymers at variable temperatures indicate the absence of Pt(iii) species. Both pure dark-green [PtL] polymers showed a considerable room temperature electrical conductivity of 20-30 S cm, which evidences the formation of a mixed valence Pt(ii)/Pt(iv) system. We discovered that these 1D polymeric [PtL] complexes show an intense NIR fluorescence beyond 1000 nm, while yellow monomeric PtL complexes are not emissive at all. The room temperature excitation spectra of 1D polymeric [PtL] complexes demonstrated their strong emission beyond 1000 nm regardless of the used excitation wavelength between 350 and 800 nm, which is typical of systems with delocalized charge carriers. For the first time the formation of mixed valence "metal wires" held together by metallophilic interactions is directly linked both with an intense fluorescence in the NIR region of the spectrum and with the electrical conductivity. The effect of the concentration of [PtL] complexes dispersed in the dielectric salt matrix on the photoluminescence wavelength and intensity was investigated. Both polymers show a quantum yield that is remarkably high for this region of the spectrum, reaching ∼2%. Variable temperature emission of polymeric [PtL] in the -190-+60 °C range was studied as well.
已获得几种含有两个氰肟阴离子——2-肟基-2-氰基-N-哌啶乙酰胺（PiPCO）和2-肟基-2-氰基-N-吗啉乙酰胺（MCO）——的“PtL”组成的配合物，并对其在溶液和固态中的性质进行了表征。配合物以两种不同的多晶型形式存在：单体黄色配合物和深绿色[PtL]一维聚合物，而对于MCO阴离子，还分离出了一种红色的、含溶剂的二聚体[Pt(MCO)·DMSO]配合物。研究了多晶型之间的相互转化。单体PtL单元借助Pt-Pt亲金属相互作用排列成各向异性的延伸固态[PtL]聚合物。测定了单体PtL（L = PiPCO，MCO）和红色二聚体[Pt(MCO)·DMSO]配合物的晶体结构，揭示了氰肟阴离子的顺式排列。发现“头对尾”红色二聚体中的Pt-Pt距离为3.133 Å。使用EXAFS方法阐明了聚合物[Pt(PiPCO)]化合物的结构，证明形成了金属间间距约为3.15 Å的Pt线。两种一维聚合物在可变温度下的EPR光谱表明不存在Pt(III)物种。两种纯深绿色[PtL]聚合物在室温下均表现出相当可观的电导率，为20 - 30 S/cm，这证明形成了混合价Pt(II)/Pt(IV)体系。我们发现这些一维聚合物[PtL]配合物在1000 nm以上表现出强烈的近红外荧光，而黄色单体PtL配合物则完全不发光。一维聚合物[PtL]配合物的室温激发光谱表明，无论在350至800 nm之间使用何种激发波长，它们在1000 nm以上均有强烈发射，这是具有离域电荷载流子的体系的典型特征。首次将通过亲金属相互作用结合在一起的混合价“金属线”的形成与光谱近红外区域的强烈荧光以及电导率直接联系起来。研究了分散在介电盐基质中的[PtL]配合物浓度对光致发光波长和强度的影响。两种聚合物在此光谱区域均表现出非常高的量子产率，达到约2%。还研究了聚合物[PtL]在 - 190 - +60 °C范围内的变温发射。
