- Study on second harmonic generation of 9-benzylidene-substituted-10-methyl-9,10-dihydroacridines
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Eight 9-benzylidene-substituted-10-methyl-9,10-dihydroacridine derivatives were synthesized from acridine as starting material and were characterized by 1H-NMR, 13C-NMR, Ms and elemental analysis. The second harmonic generation (SHG) values of these compounds were determined in powder using Nd:YAG as a laser source, as compared with urea powder, and the values of second-order polarizabilities (βxxx), the values of the composite magnitude (βCTμg) of molecular hypersusceptibilities and their moment of these compounds were obtained by the solvatochromic method under ground state for everyone. The results showed that SHG value of 10 is higher than that of urea; the βCTμg of 5 (107.8 × 10-30 esu) is lower than that of 4-nitro-N,N-dimethylaniline (30 × 10-30 esu); the βCTμg of 7 (350.8 × 10-30 esu) and 10 (244.6 × 10-30 esu) are higher than that of 4-nitro-N,N-dimethylaniline; the βCTμg of 8 (3553 × 10-30 esu), 11 (1187 × 10-30 esu) and 12 (1163 × 10-30 esu) are much more higher than that of 4-nitro-N,N-dimethylaniline. The results demonstrated that this series of compounds possesses good second-order nonlinear optical (NLO) property. The regular relationship could not be obtained between electronegativity of substituents (R) attached to benzylidene ring and SHG values or βCTμg values although the Rs are different in electronegativity and should make an effect on the extent of intramolecular electron-transfer and would consequently influence SHG or βCTμg. The electron-withdrawing ability of R from benzylidene ring played an important role on λmax of these compounds.
- Song,Jin,Zheng,Ying
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- Pd-Catalyzed Autotandem Reactions with N-Tosylhydrazones. Synthesis of Condensed Carbo- and Heterocycles by Formation of a C-C Single Bond and a C-C Double Bond on the Same Carbon Atom
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A new Pd-catalyzed autotandem reaction is introduced that consists of the cross-coupling of a benzyl bromide with a N-tosylhydrazone followed by an intramolecular Heck reaction with an aryl bromide. During the process, a single and a double C-C bond are formed on the same carbon atom. Two different arrangements for the reactive functional groups are possible, rendering great flexibility to the transformation. The same strategy led to 9-methylene-9H-fluorenes, 9-methylene-9H-xanthenes, 9-methylene-9,10-dihydroacridines, and also dihydropyrroloisoquinoline and dihydroindoloisoquinoline derivatives.
- Paraja, Miguel,Valdés, Carlos
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p. 2034 - 2037
(2017/04/27)
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- Experimental evidence of the occurrence of intramolecular electron transfer in catalyzed 1,2-dioxetane decomposition
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The activation parameters for the thermal decomposition of 13 acridinium-substituted 1,2-dioxetanes, bearing an aromatic moiety, were determined and their chemiluminescence emission quantum yields estimated, utilizing in situ photosensitized 1,2-dioxetane generation and observation of its thermal decomposition kinetics, without isolation of these highly unstable cyclic peroxides. Decomposition rate constants show linear free-energy correlation for electron-withdrawing substituents, with a Hammett reaction constant of Φ = 1.3 ± 0.1, indicating the occurrence of an intramolecular electron transfer from the acridinium moiety to the 1,2-dioxetane ring, as postulated by the intramolecular chemically initiated electron exchange luminescence (CIEEL) mechanism. Emission quantum yield behavior can also be rationalized on the basis of the intramolecular CIEEL mechanism, additionally evidencing its occurrence in this transformation. Both relations constitute the first experimental evidence for the occurrence of the postulated intramolecular electron transfer in the catalyzed and induced decomposition of properly substituted 1,2-dioxetanes.
- Ciscato, Luiz Francisco M. L.,Bartoloni, Fernando H.,Weiss, Dieter,Beckert, Rainer,Baader, Wilhelm J.
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supporting information; experimental part
p. 6574 - 6580
(2010/11/17)
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- Structural Effects on the Intramolecular Electron Transfer Induced Decomposition of a Series of 1,2-Dioxetanes Derived from 9-Alkylidene-10-methylacridans
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A series of 1,2-dioxetanes derived from 9-alkylidene-10-methylacridans, Ar=CR1R2, were studied: 5, R1=R2=phenyl; 1, R1=phenyl, R2=H; 6, R1=R2=H.Thermal decomposition of these dioxetanes in the temperature range -30 to +35 deg C is accompanied by chemiluminescence (CL), N-methylacridone(NMA) fluorescence, with representative room temperature ΦCL's of 0.11, 0.04, and ca.10-5 and room temperature lifetimes of ca.2000, ca.60, and ca.6 s, for 5, 1, and 6, respectively.The only triplet states produced in these system is by 1NMA* 3NMA* as indicated by triplet counting experiments.The CL from decomposition of 1 is subject to off/on switching by successive addition of acetic acid and triethylamine.The proposed mechanism involves intramolecular electron transfer (N to peroxide bond) induced decomposition, via a boat conformation, to a dipolar intermediate that partitions between chemiexcitation and nonchemiexcitation pathways.The related low CL levels from decomposition of 1 when prepared by triphenyl phosphite ozonide oxygenation, and the CL enhancement with added triethylamine, are explained.
- Lee, Chris,Singer, Lawrence A.
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p. 3823 - 3829
(2007/10/02)
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