A Series of D–A–D Structured Disilane-Bridged Triads: Structure and Stimuli-Responsive Luminescence Studies

Abstract

A series of σ−π extended octamethyltetrasilanes, which have phenothiazine, 9,9-dimethyl-9,10-dihydroacridine, or phenoxazine (1, 2, and 3) groups as donor moieties and thienopyrazine or benzothiadiazole (a and b) groups as acceptor fragments, has been prepared, and their optical properties have been studied as an extension of our work. All six compounds exhibited fluorescence in the solid state with maximum wavelengths centered in the range of 400 and 650 nm upon excitation by a UV lamp. Compound 2b showed apparent dual emission behavior in solution, which depends on solvent polarity, and a reversible photoluminescent change under mechanical and thermal stimuli in the solid state. Quantum chemical calculations suggest the contribution of a quasi-axial conformer of the 9,9-dimethyl-9,10dihydroacridine moiety in 2b to the dual emission in solution and the mechanofluoroluminescence in the solid state, similarly to 1a. These studies provide new insight into the preparation of disilane-bridged triads capable of responding to multiple stimuli.

Hydrosilane/Organoiodine Coupling-Enabled Studies of Organosilane Physical Properties

“…Phenothiazine and its derivatives exhibit conformational changes under weak external stimuli in the crystalline state . Based on the properties, a series of σ–π extended octamethyltetrasilanes 34 – 39 , which have phenothiazine, 9,9-dimethyl-9,10-dihydroacridine, or phenoxazine groups as donor moieties and thienopyrazine or benzothiadiazole groups as acceptor fragments, was prepared to improve the stimuli-responsiveness. ,, All six compounds exhibited very weak emission in solution (Φ F < 0.01), but exhibit intense solid-state emission (Φ F : 0.01–0.11) with maximum wavelengths in the range of 400 and 650 nm upon excitation by UV (Figure ). Compounds 34 and 37 showed a reversible photoluminescent change under mechanical and thermal or vapor fuming stimuli in the solid state. − Quantum chemical calculations suggested a contribution of a quasi-axial conformer of phenothiazine and 9,9-dimethyl-9,10-dihydroacridine moieties to the dual emission in solution and mechanochromic fluorescence in the solid state.…”

Convenient One-Pot Synthesis of L2Pd(0) Complexes for Cross-Coupling Catalysis

“…Examples include the synthesis of bioactive molecules such as xishacorene B, an immunopotentiator; Rucaparib, an anticancer agent; methoxy myolic acid, an antigen; and an antihypercholesterolemic compound on multikilogram scale by Limanto and co-workers at Merck & Co . Other applications in the areas of materials science include the synthesis of organic electroluminescent materials used for thin-film and optical sensor applications by Yamanoi and co-workers …”

“…Examples include the synthesis of bioactive molecules such as xishacorene B, an immunopotentiator; 14 Rucaparib, an anticancer agent; 10 methoxy myolic acid, an antigen; 13 and an antihypercholesterolemic compound on multikilogram scale by Limanto and co-workers at Merck & Co. 35 Other applications in the areas of materials science include the synthesis of organic electroluminescent materials used for thin-film and optical sensor applications by Yamanoi and co-workers. 36 Due to the rising cost and increasing scarcity of precious metals such as palladium, it is becoming difficult to sustain its usage in many applications, including catalysis. To continue the supply of these important catalysts, operationally simple, atom-and step economical, and cost-effective procedures must be developed to minimize the loss of metal with a goal to maximize the yield and output.…”

15N CP/MAS NMR as a Tool for the Mechanistic Study of Mechanical Stimuli-Responsive Materials: Evidence for the Conformational Change of an Emissive Dimethylacridane Derivative

“…We recently reported emissive organosilane crystalline compounds with nitrogen atoms in heterocyclic components . These compounds exhibit mechanochromic luminescence owing to a combination of the flexibility of the Si–Si bond and the conformational isomers of the cyclic N -arylamine. , Among them, 4,7-bis­(2-(4-(9,9-dimethylacridin-10­(9 H )-yl)­phenyl)-1,1,2,2-tetramethyldisilanyl)­benzo­[ c ]­[1,2,5]­thiadiazole adopts various conformational isomers 1α , 1β , and 1γ , which contribute to changes in luminescence properties (Figure ). The conformational structure in the crystalline state was found as 1α studied by X-ray diffraction experiments.…”