TY - JOUR

T1 - Binuclear Gold(I) Phosphine Alkynyl Complexes Templated on a Flexible Cyclic Phosphine Ligand

T2 - Synthesis and Some Features of Solid-State Luminescence

AU - Strelnik, Igor D.

AU - Sizov, Vladimir V.

AU - Gurzhiy, Vladislav V.

AU - Melnikov, Alexei S.

AU - Kolesnikov, Ilya E.

AU - Musina, Elvira I.

AU - Karasik, Andrey A.

AU - Grachova, Elena V.

N1 - Funding Information: The authors greatly appreciate financial support from the Russian Science Foundation (Grant 19-43-04119). The work was carried out using equipment of St. Petersburg State University Research Park (Centres of Magnetic Resonance, Optical and Laser Materials Research, Chemical Analysis and Materials Research; X-ray Diffraction Centre, and Computational Centre), the Analytical Centre for Nano- and Biotechnologies (Peter the Great St. Petersburg Polytechnic University, with financial support from the Ministry of Education and Science of Russian Federation), and the Centre of Collective Usage of FRC KSC, RAS. The authors thank Dr. Tatiana P. Gerasimova (Arbuzov Institute of Organic and Physical Chemistry, FRC KSC, RAS) for helpful suggestions and discussion.

PY - 2020/1/6

Y1 - 2020/1/6

N2 - 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.

AB - 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.

UR - http://www.scopus.com/inward/record.url?scp=85076815715&partnerID=8YFLogxK

U2 - 10.1021/acs.inorgchem.9b02091

DO - 10.1021/acs.inorgchem.9b02091

M3 - Article

AN - SCOPUS:85076815715

VL - 59

SP - 244

EP - 253

JO - Inorganic Chemistry

JF - Inorganic Chemistry

SN - 0020-1669

IS - 1

ER -