Guang-Ao Yu

Aggregation-induced emission-active gold(I) complexes with multi-stimuli luminescence switching

A series of diisocyano-based dinuclear gold(I) complexes have been synthesized, differing only in the bridge linking the two (identical) arms. All of these complexes have been thoroughly characterized by NMR and IR spectroscopy and elemental analysis. The gold(I) complexes 1a, 1b and 1c all exhibit aggregation-induced emission (AIE) characteristics and mechanochromic behavior; their phosphorescence properties show reversible switchable off–on green luminescence in response to grinding. We have investigated the origins of these phenomena by spectroscopy, phosphorescence quantum yields and X-ray powder diffraction. From the experimental data, we conclude that the changing of multiple intermolecular C–H⋯F, C⋯F, weak π–π interactions and the formation of aurophilic interactions are critical elements that determine the AIE-active and switchable mechanochromic luminescence.

Experimental and Theoretical Studies of Charge Delocalization in Biruthenium–Alkynyl Complexes Bridged by Thiophenes

A series of binuclear ruthenium-alkynyl complexes that are bridged by thiophene groups (thiophene, bithiophene, and terthiophene) have been synthesized. All of these complexes have been well-characterized by NMR spectroscopy, X-ray diffraction, and elemental analysis. The electronic properties of these complexes have been examined by using cyclic voltammetry, UV/Vis/NIR and IR spectroscopy, electron paramagnetic resonance (EPR) spectroscopy, and density functional theory (DFT) calculations. Electrochemical results showed that the potential difference (ΔE) and comproportionation constant (Kc) decreased with increasing size of the thiophene bridging unit. The UV/Vis/NIR spectra and TDDFT calculations of the monocations indicated that the NIR transitions displayed aromatic bridging character. EPR studies of the mono-oxidized radical species further demonstrated that the unpaired electron/hole was delocalized over both metals and the bridging ligand and established significant participation in the ligand oxidation.

Bridge-localized HOMO-binding character of divinylanthracene-bridged dinuclear ruthenium carbonyl complexes: spectroscopic, spectroelectrochemical, and computational studies.

The electronic properties of four divinylanthracene-bridged diruthenium carbonyl complexes [{RuCl(CO)(PMe3)3}2(μ-CH=CHArCH=CH)] (Ar=9,10-anthracene (1), 1,5-anthracene (2), 2,6-anthracene (3), 1,8-anthracene (4)) obtained by molecular spectroscopic methods (IR, UV/Vis/near-IR, and EPR spectroscopy) and DFT calculations are reported. IR spectroelectrochemical studies have revealed that these complexes are first oxidized at the noninnocent bridging ligand, which is in line with the very small ν(C≡O) wavenumber shift that accompanies this process and also supported by DFT calculations. Because of poor conjugation in complex 1, except oxidized 1(+), the electronic absorption spectra of complexes 2(+), 3(+), and 4(+) all display the characteristic near-IR band envelopes that have been deconvoluted into three Gaussian sub-bands. Two of the sub-bands belong mainly to metal-to-ligand charge-transfer (MLCT) transitions according to results from time-dependent DFT calculations. EPR spectroscopy of chemically generated 1(+)-4(+) proves largely ligand-centered spin density, again in accordance with IR spectra and DFT calculations results.

Fluorene-based novel gold(I) complexes with aggregation-induced emission (AIE) or aggregate fluorescence change characteristics: from green to white emission

In this paper, five fluorene-based gold(I) complexes are synthesized and characterized. They exhibit typical aggregation-induced emission (AIE) properties or significant aggregate fluorescence change behaviors. Their thin-film and solid state fluorescence spectra are consistent with the luminescence of all luminogens in DMF–H2O mixtures with high water content. The emission color changes with different numbers of fluorene units. Among them, it is remarkable that luminogens 4 and 5 emit a bright white light in the thin-film and solid state. In addition, their thin-film absolute fluorescence quantum yields are also investigated. The results indicate the luminogen 4 gold(I) complex, with three fluorene units, exhibits the highest thin-film emission quantum yield, which is up to 65.42%.

Chiral gamma-aryl-1H-1,2,4-triazole derivatives as highly potential antifungal agents: Design, synthesis, structure, and in vitro fungicidal activities.

A novel series of chiral gamma-aryl-1H-1,2,4-triazole derivatives as highly potential antifungal agents have been designed and synthesized conveniently by using the chiral auxiliary as a controlling reagent. All of the compounds exhibit moderate to high ee values reaching up to 99%, and the preliminary bioassay results demonstrated that most of the target compounds take on a significantly wide spectrum activity against Fusarium oxysporium, Rhizoctonia solani, Botrytis cinereapers, Gibberella zeae, Dothiorella gregaria, and Colletotrichum gossypii species.

1,8-Naphthalimide-based highly blue-emissive fluorophore induced by a bromine atom: reversible thermochromism and vapochromism characteristics

We report a structurally simple 1,8-naphthalimide-based fluorescent molecule. Its solid shows an intense blue emission with an absolute fluorescence quantum yield of up to 82.33%. The novel luminogen exhibits reversible thermochromism and vapochromism behaviors.

Phenylphosphinacalix[3]trifuran: synthesis, coordination and application in the Suzuki–Miyaura cross-coupling reaction in water

Phenylphosphinacalix[3]trifuran and supramolecular assemblies with palladium have been synthesized. Phenylphosphinacalix[3]trifuran affords turnover numbers as high as 3.05 × 107 in Suzuki–Miyaura cross-coupling reactions in pure water.

Carbazole-based gold(I) complexes with alkyl chains of different lengths: tunable solid-state fluorescence, aggregation-induced emission (AIE), and reversible mechanochromism characteristics

In this paper, seven carbazole-based mononuclear gold(I) complexes with alkyl chains of different lengths have been synthesized and reported. All of these gold(I) complexes exhibit outstanding AIE characteristics. Furthermore, these various solid-state light-emitting AIE-active gold(I) complexes all show reversible mechanochromic fluorescent behaviors. The possible mechanism explaining these interesting AIE and mechanochromism phenomena involves a variation in weak multiple intermolecular C–H⋯F and π⋯π interactions and the formation or alteration of aurophilic interactions.

Phenyl substituted indenylphosphine ruthenium complexes as catalysts for dehydrogenation of alcohols

Thermal treatment of (1H-inden-3-yl)dicyclohexylphosphinium tetrafluoroborate (1) and (3-mesityl-1H-inden-3-yl)dicyclohexylphosphinium tetrafluoroborate (3) with tBuONa followed by [(η(6)-cymene)RuCl(2))](2) in methanol gave the adduct {(η(6)-cymene)RuCl(2)[(1H-inden-3-yl)PCy(2)]} (6) and {(η(6)-cymene)RuCl(2)[(3-mesityl-1H-inden-3-yl)PCy(2)]} (7), respectively. Thermal treatment of (2-phenyl-1H-inden-3-yl)dicyclohexylphosphinium tetrafluoroborate (4) with tBuONa followed by [(η(6)-cymene)RuCl(2))](2) or RuCl(3)·3H(2)O in methanol gave {Ru[κ(P):(η(6)-2-phenyl-1H-inden-3-yl)PCy(2)]Cl(2)} (8). Whereas (2-mesityl-1H-inden-3-yl)dicyclohexylphosphine (5) reacted with [(η(6)-cymene)RuCl(2))](2) (in toluene) or RuCl(3)·3H(2)O (in ethanol) to afford {Ru[κ(P):(η(6)-2-mesityl-1H-inden-3-yl)PCy(2)]Cl(2)} (9). The molecular structures of complexes 6, 8 and 9 have been determined by single-crystal X-ray diffraction analysis. In addition, complexes 8 and 9 have been found to catalyze the acceptorless dehydrogenation of alcohols in toluene. 9 displayed high activity and different substrates, including cyclic and linear alcohols, were efficiently oxidized to ketones by using 2.0 mol% of catalyst.

2Rotaxane based on terpyridyl bimetal ruthenium complexes and β-cyclodextrin as organic sensitizer for dye-sensitized solar cells

The conjugated carboxy-functionalized terpyridyl bimetal ruthenium complex [(tdctpy)Ru(dctpy-(ph)4-dctpy)Ru(tdctpy)][PF6]4 and [2]rotaxane by self-assembly of [(tdctpy)Ru(dctpy-(ph)4-dctpy)Ru(tdctpy)][PF6]4 with β-cyclodextrin are reported as sensitizer for dye-sensitized solar cells (DSSCs), where tdctpy = 4′-p-tolyl-4,4″-dicarboxy-2,2′ : 6,2″-terpyridine, dctpy = 4,4″-dicarboxy-2,2′ : 6,2″-terpyridine and dctpy-(ph)4-dctpy represents a bridging ligand where two 4,4″-dicarboxy-2,2′ : 6′,2″-terpyridine units are connected through four phenyl spacers in the 4′-position. The DSSCs fabricated utilizing these materials give typical electric power conversion efficiency of 0.013–0.523% under air mass (AM) 1.5, 100 mW cm−2 irradiation at room temperature. The terpyridyl bimetal ruthenium complex [(tdctpy)Ru(dctpy-(ph)4-dctpy)Ru(tdctpy)][PF6]4 with conjugated-bridge chains displayed much higher conversion efficiency compared with the carboxy-functionalized terpyridyl monometal ruthenium complex [tdctpy-Ru-(idctpy)][PF6]2, where idctpy = 4′-p-iodophenyl-4,4″-dicarboxy-2,2′ : 6,2″-terpyridine. [2]Rotaxane displayed the highest electric power conversion efficiency of 0.523% when β-cyclodextrin was introduced into the conjugated terpyridyl bimetal ruthenium complex and formed [2]rotaxane.