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

Abstract

A flexible bidentate cyclic phosphine, namely, 1,5-bis(ptolyl)-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(AuC 2 R) 2 ], with R = Ph, C 6 H 10 OH, C 5 H 8 OH, (CH 3 ) 2 COH, Ph 2 COH. 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 Ph 2 COH 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.

Alkynylgold(I) C3‐Chiral Concave Complexes: Aggregation and Luminescence

“…Gold(I) alkynyl complexes with phosphine or isonitrile ancillary ligands, since the first report in 1959, [1] received increasing attention after their unique photophysical properties, [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20] coupled to the possibility of intramolecular aurophilic interactions in polynuclear complexes, [21][22][23][24][25][26][27] and intermolecular Au•••Au short contacts in the solid state [5,[28][29][30] or in supramolecular assemblies [31][32][33] had been recognized. [34,35] The interest in these compounds was currently raised by the applications [36] of their luminescence properties to the development of materials for (opto)electronics, [37,38] sensing, [23,26,27,39,40] and cellular imaging.…”

Assembly of Heterometallic AuICu2I2 Cores on the Scaffold of NPPN-Bridging Cyclic Bisphosphine

“…The diphosphine ligands in complexes 4 and 5 adopt a chair-boat conformation with a twisted boat part and with an axial orientation of substituents at the nitrogen atoms and equatorial orientation of substituents at the phosphorus atoms. Differences in the gold­(I) ions positions in complexes 4 and 5 are the result of different coordination environments of gold cations as well as the relative lability of the aminomethylphosphine cycle, which allows the realization of the rotative movement of both phosphorus atoms …”

“…Differences in the gold(I) ions positions in complexes 4 and 5 are the result of different coordination environments of gold cations as well as the relative lability of the aminomethylphosphine cycle, which allows the realization of the rotative movement of both phosphorus atoms. 45 The crystal packing of 4 displays channels located between two layers of cationic complexes and occupied by disordered chloride anions. In complex 5, iodide ions are shielded by bulky 1,5-diaza-3,7-diphosphacyclooctanes and the shortest distance between iodide in neighboring molecules is 5.88 Å; the space between complexes is occupied by DMF molecules.…”

Thermo-responsive light-emitting metal complexes and related materials

“…11). 100 This complex exhibited very weak greenish emission in solution at rt. Upon cooling to 180 K, a slight blue shift of the emission spectrum with a significant intensity enhancement was observed, mainly attributed to the configuration rigidification of 12 at low temperatures.…”