Binuclear Gold(I) Phosphine Alkynyl Complexes Templated on a Flexible Cyclic Phosphine Ligand: Synthesis and Some Features of Solid-State Luminescence.

A flexible bidentate cyclic phosphine, namely, 1,5-bis(p-tolyl)-3,7-bis(pyridin-2-yl)-1,5-diaza-3,7-diphosphacyclooctane (PNNP), was used as a template to construct a family of binuclear heteroleptic phosphine alkynyl complexes [PNNP(AuC2R)2], with R = Ph, C6H10OH, C5H8OH, (CH3)2COH, Ph2COH. All complexes obtained were characterized by CHN elemental analysis, NMR spectroscopy, and single-crystal X-ray analysis. It was found that the gold(I) complexes demonstrate a different organization of the crystal structure depending on the nature of the cocrystallized solvent (dichloromethane, acetone, and acetonitrile) because of formation of the supramolecular complexes through hydrogen bonding. These weak interactions appear to determine the conformation, packing, and spatial cooperation of flexible complex molecules that are reflected in the photophysical properties, which were carefully investigated in solution and in the solid state. The complexes demonstrate weak emission in solution at room temperature, and freezing results in blue shifting of the emission, which is accompanied by a significant increase in the luminescence intensity. Being isolated from dichloromethane, all gold(I) complexes exhibit green phosphorescence in the solid state, and the complexes with R = Ph and Ph2COH display substantial variation of their emission color after recrystallization from acetone and acetonitrile, respectively, which manifests itself as a significant bathochromic shift of up to 120 nm. The structural nonrigidity of the gold(I) complexes obtained and its impact on the properties of low-energy excited states were investigated in detail by density functional theory calculations, which indicate the significant role of the structural flexibility of the PNNP ligand in the formation of the low-energy excited states and confirm the impact of rotation of the functional groups in the coordination sphere on the emission properties of complexes.

[1]  E. Hey‐Hawkins,et al.  Novel representatives of 16-membered aminomethylphosphines with alkyl substituents at nitrogen and their gold(I) complexes , 2018, Russian Chemical Bulletin.

[2]  J. Vicente,et al.  The Coordination and Supramolecular Chemistry of Gold Metalloligands. , 2018, Chemistry.

[3]  K. Brylev,et al.  Novel water soluble cationic Au(I) complexes with cyclic PNNP ligand as building blocks for heterometallic supramolecular assemblies with anionic hexarhenium cluster units , 2017 .

[4]  Quan‐Ming Wang,et al.  Full Protection of Intensely Luminescent Gold(I)-Silver(I) Cluster by Phosphine Ligands and Inorganic Anions. , 2017, Angewandte Chemie.

[5]  P. Chou,et al.  Harnessing Fluorescence versus Phosphorescence Ratio via Ancillary Ligand Fine-Tuned MLCT Contribution , 2016 .

[6]  Chiara Botta,et al.  Cu(I) hybrid inorganic-organic materials with intriguing stimuli responsive and optoelectronic properties , 2016 .

[7]  P. Chou,et al.  Tetragold(I) complexes: solution isomerization and tunable solid-state luminescence. , 2014, Inorganic chemistry.

[8]  P. Chou,et al.  Luminescent Gold(I) Alkynyl Clusters Stabilized by Flexible Diphosphine Ligands , 2014 .

[9]  E. Hey‐Hawkins,et al.  New functional cyclic aminomethylphosphine ligands for the construction of catalysts for electrochemical hydrogen transformations. , 2014, Chemistry.

[10]  T. Pakkanen,et al.  Ferrocenyl-Functionalized Tetranuclear Gold(I) and Gold(I)–Copper(I) Complexes Based on Tridentate Phosphanes , 2013 .

[11]  P. Chou,et al.  Harnessing Fluorescence versus Phosphorescence Branching Ratio in (Phenyl)(n)-Bridged (n=0-5) Bimetallic Au(I) Complexes , 2013 .

[12]  Daniel Volz,et al.  How the quantum efficiency of a highly emissive binuclear copper complex is enhanced by changing the processing solvent. , 2013, Langmuir : the ACS journal of surfaces and colloids.

[13]  O. Wenger,et al.  Vapochromism in organometallic and coordination complexes: chemical sensors for volatile organic compounds. , 2013, Chemical reviews.

[14]  P. Chou,et al.  Intensely luminescent homoleptic alkynyl decanuclear gold(I) clusters and their cationic octanuclear phosphine derivatives. , 2012, Inorganic chemistry.

[15]  B. Li,et al.  Luminescence vapochromism in solid materials based on metal complexes for detection of volatile organic compounds (VOCs) , 2012 .

[16]  P. Chou,et al.  Modulation of metallophilic bonds: solvent-induced isomerization and luminescence vapochromism of a polymorphic Au-Cu cluster. , 2012, Journal of the American Chemical Society.

[17]  Philip Coppens,et al.  Restricted photochemistry in the molecular solid state: structural changes on photoexcitation of Cu(I) phenanthroline metal-to-ligand charge transfer (MLCT) complexes by time-resolved diffraction. , 2012, The journal of physical chemistry. A.

[18]  J. C. Lima,et al.  Applications of gold(I) alkynyl systems: a growing field to explore. , 2011, Chemical Society reviews.

[19]  J. López‐de‐Luzuriaga,et al.  Influence of the electronic characteristics of N-donor ligands in the excited state of heteronuclear gold(I)-copper(I) systems. , 2011, Inorganic chemistry.

[20]  Wai-Yeung Wong,et al.  Organometallic acetylides of Pt(II), Au(I) and Hg(II) as new generation optical power limiting materials. , 2011, Chemical Society reviews.

[21]  N. Handy,et al.  A new hybrid exchange–correlation functional using the Coulomb-attenuating method (CAM-B3LYP) , 2004 .

[22]  Richard Eisenberg,et al.  Intensely luminescent gold(I)-silver(I) cluster complexes with tunable structural features. , 2004, Journal of the American Chemical Society.

[23]  Vivian Wing-Wah Yam,et al.  Luminescent polynuclear d10 metal complexes , 1999 .