220721-30-2Relevant academic research and scientific papers
Bespoke photoreductants: Tungsten arylisocyanides
Sattler, Wesley,Henling, Lawrence M.,Winkler, Jay R.,Gray, Harry B.
, p. 1198 - 1205 (2015)
Modular syntheses of oligoarylisocyanide ligands that are derivatives of 2,6-diisopropylphenyl isocyanide (CNdipp) have been developed; tungsten complexes incorporating these oligoarylisocyanide ligands exhibit intense metal-to-ligand charge-transfer visible absorptions that are red-shifted and more intense than those of the parent W(CNdipp)6 complex. Additionally, these W(CNAr)6 complexes have enhanced excited-state properties, including longer lifetimes and very high quantum yields. The decay kinetics of electronically excited W(CNAr)6 complexes (W(CNAr)6) show solvent dependences; faster decay is observed in higher dielectric solvents. W(CNAr)6 lifetimes are temperature dependent, suggestive of a strong coupling nonradiative decay mechanism that promotes repopulation of the ground state. Notably, W(CNAr)6 complexes are exceptionally strong reductants: [W(CNAr)6]+/W(CNAr)6 potentials are more negative than -2.7 V vs [Cp2Fe]+/Cp2Fe. (Figure Presented).
Photophysical processes in rhenium(I) diiminetricarbonyl arylisocyanides featuring three interacting triplet excited states
Favale, Joseph M.,Danilov, Evgeny O.,Yarnell, James E.,Castellano, Felix N.
, p. 8750 - 8762 (2019/08/20)
We present a series of four transition-metal complexes based on the rhenium(I) tricarbonyl 1,10-phenanthroline (phen) template, with a lone ancillary arylisocyanide (CNAr) ligand to yield metal-organic chromophores of the generic molecular formula [Re(phen)-(CO)3(CNAr)]+ [CNAr = 2,6-diisopropylphenyl isocyanide (1), 4-phenyl-2,6-diisopropylphenyl isocyanide (2), 4-phenylethynyl-2,6-diisopropylphenyl isocyanide (3), and 4-biphenyl-2,6-diisopropylphenyl isocyanide (4)]. This particular series features varied degrees of π-conjugation length in the CNAr moiety, resulting in significant modulation in the resultant photophysical properties. All molecules possess long-lived [8- 700 μs at room temperature (RT)], strongly blue-green photoluminescent and highly energetic excited states λmax,em = 500-518 nm; Φ = 14-64%). Each of these chromophores has been photophysically investigated using static and dynamic spectroscopic techniques, the latter probed from ultrafast to suprananosecond time scales using transient absorption and photoluminescence (PL). Time-resolved PL intensity decays recorded as a function of the temperature were consistent with the presence of at least two emissive states lying closely spaced in energy with a third nonemissive state lying much higher in energy and likely ligand-field in character. The combined experimental evidence, along with the aid of electronic structure calculations (density functional theory and time-dependent density functional theory performed at the M06/Def2-SVP/SDD level), illustrates that the CNAr ligand is actively engaged in manipulating the excited-state decay in three of these molecules (2-4), wherein the triplet metal-to-ligand charge-transfer (3MLCT) state along with two distinct triplet ligand-centered (3LC) excited-state configurations (phen and CNAr) conspire to produce the resultant photophysical properties. Because the π conjugation within the CNAr ligand was extended, an interesting shift in the dominant photophysical processes was observed. When the CNAr conjugation length is short, as in 1, the phenanthroline 3LC state dominates, resulting in a configurationally mixed triplet excited state of both LC and MLCT character. With more extended π conjugation in the CNAr subunit (2-4), the initially generated 3LC(phen)/3MLCT excited state ultimately migrates to the CNAr 3LC state on the order of tens of picoseconds. Molecules 3 and 4 in this series also feature unique examples of inorganic excimer formation, as evidenced by dynamic self-quenching in the corresponding PL intensity decays accompanied by the observation of a short-lived low-energy emission feature.
Synthesis, photophysical properties, and molecular aggregation of gold(I) complexes containing carbon-donor ligands
Chow, Andy Lok-Fung,So, Man-Ho,Lu, Wei,Zhu, Nianyong,Che, Chi-Ming
, p. 544 - 553 (2011/10/12)
A series of gold(I) complexes with N-heterocyclic carbene (NHC) and acetylide ligands, namely [Au(NHC1)(C≡CAr)] (NHC 1=1-(9-anthracenylmethyl)-3-(n)-butylimidazol-2-ylidene; 1b-1g), [Au(NHC2)(C≡CAr)] (NHC2=1,3-diethylimidazol-2- ylidene; 2b-2f) and [Au(C≡NAr)2]+ (C≡NAr=arylisocyanide; 3a-3f) have been synthesized. At room temperature, most of these gold(I) complexes are emissive in the solid state and in solutions with lifetimes in the nanosecond to submicrosecond regime. The emissions of complexes 1b-1g in solutions are assigned to 1π-π* excited states of the NHC ligand, while that of 2b-2f and 3a-3f are phosphorescent in nature. The intriguing solvatochromism of complex 3a was also investigated. Complexes 1b, 1d, 3a, and 3e aggregate into crystalline nanowires in freshly prepared THF/water dispersions. The X-ray crystallographic data reveal that 1b and 1d possess intermolecular π-π and C-H ... π interactions; while 3a was found to display intermolecular gold(I) ... π interactions. Copyright
