An International Quarterly Research Journal

ACL Vol 16 No 2

ACL

                                                                                                      ISSN : 0971 - 9822

                                                                           Vol   16,  No   2 ,  April-June,   2012

Asian Chemistry Letters                                                                                        Vol. 16, No. 2 (2012)1-8


Computational details of calculated UV-VIS and CD spectra of a salen type of

chiral Schiff base Ni(II) complex


Atsuo Yamazaki, Tomoaki Hiratsuka, and Takashiro Akitsu*

Department of Chemistry, Faculty of Science, Tokyo University of Science

1-3Kagurzaka, Shinjuku-ku, Tokyo 162-8601, Japan

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Recently, we have reported chriptical properties of a series of chiral salen-type Schiff base 3d-4f binuclear (Ln(III)-M(II)) complexes and their related 3d mononuclear (M(II)) complexes [in Crystallography: Research, Technology and Applications]. In this study, we could observe characteristic chiroptical features in CD bands due to these 3d-4f binuclear units in the solid states. Systematically comparison of solid-state CD and electronic spectra revealed that introduction and substitution of 4f ions resulted in predominant shift of CT and p-p* bands. In order to interpret these spectra, we simulated both CD and electronic spectra with ZINDO calculations. Herein, we report on detailed results of computation of a mononuclear Ni(II) complex as a standard compounds and assignment of transitions as well as bands.

Total Refs : 23

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Asian Chemistry Letters                                                                                      Vol. 16, No. 2 (2012)9-18


Preparations of hybrid systems of L-amino acid derivatives of Schiff base Cu(II) and

Zn(II) complexes and polyoxometalates


Yoshimasa Watanabe and Takashiro Akitsu*

Department of Chemistry, Faculty of Science, Tokyo University of Science

1-3Kagurzaka, Shinjuku-ku, Tokyo 162-8601, Japan

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We have prepared new chiral Schiff base copper(II) (Cu) or zinc(II) (Zn) complexes formed by L-amino acids derivatives, namely alanine (A) or glycine (G), and aldehydes, namely 3,5-dichlorosalicylaldehyde (3) or salicylaldehyde (S), abbreviated as CuA3, CuAS, CuG3, CuGS, ZnA3, ZnAS, ZnG3, and ZnGS, respectively. They are and characterized with UV-vis, CD, and IR spectra, cyclic voltammetry, and crystal structure analysis. Although CuA3, CuAS, CuG3, and CuGS are mononuclear complexes, only crystals of CuAS are isolated as a form having imidazole ligand. In solutions or as precipitates, ZnA3, ZnAS, ZnG3, and ZnGS are also mononuclear complexes, while crystal structures suggested that the zinc(II) complexes are bridged with the fourth coordination sites in the crystals. In order to discuss intermolecular interaction accompanying with electron transfer reactions potentially, hybrid systems of several types of (known) polyoxometalates and the chiral Schiff base copper(II) or zinc(II) complexes were investigated. Decreasing of fluorescence intensity due to quenching could be observed for zinc(II) complexes obviously. Stereochemical discussion with MM2 calculation was also employed to estimate molecular structures in solutions.

Total Refs : 25

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Asian Chemistry Letters                                                                                    Vol. 16, No. 2 (2012)19-32


Conformational calculations of trans-Schiff base metal complexes for endothermal

oraganic/inorganic fillers in flame retardant polymers


Yutaro Aota and Takashiro Akitsu*

Department of Chemistry, Faculty of Science, Tokyo University of Science

1-3Kagurzaka, Shinjuku-ku, Tokyo 162-8601, Japan

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In order to apply flame retardant additives for polymer materials, we focused on trans-type Schiff base metal complexes, which are expected to act as thermodynamically endotharmal reagents to inhibit raising temperature of polymers by absorbing enthalpy. In this study, we have calculated the differences of heat of formation between crystal structures and optimized structures by MM2.The present computational study suggests that introducing bulky groups in trans- type Schiff base metal complexes are potentially good flame retardant additives for polymer materials.

Total Refs : 24

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Asian Chemistry Letters                                                                                    Vol. 16, No. 2 (2012)33-42


Photo-induced reduction of hybrid systems of phenylalanine and other derivatives of Schiff

base Cu(II) complexes and titanium(IV) oxide


Hitoe Nishizuru, Naoko Kimura, and Takash Akitsu*

Department of Chemistry, Faculty of Science, Tokyo University of Science

1-3Kagurzaka, Shinjuku-ku, Tokyo 162-8601, Japan

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We have prepared and characterized new five chiral Schiff base copper(II) complexes incorporating phenylalanine, tyrosine, methionine, isoleucine, and histidine L-amino acids derivatives, abbreviated as CuPhe, CuTyr, CuMet, CuIle, and CuHis, respectively. Although CuPhe, CuTyr, CuMet, and CuIle are mononuclear complexes, only CuHis affords a dinuclear structure bridged via imidazole moieties. Similar to the analogous copper(II) complexes with L-amino acids derivatives or some other mononuclear copper(II) complexes, hybrid systems of small particles of TiO2 and the present four mononuclear complexes exhibited decreasing intensity of d-d bands after irradiation UV light under nitrogen atmosphere, which was considered as reduction of copper(II) ions to copper(I) ones by photocatalysis. Spectral changes of near UV region were also examined for typical example CuPhe. However, only CuHis did not exhibit such reaction. Stereochemical discussion with MM2 calculation was also given to form a dinucler complex which was inactive to this reaction.

Total Refs : 25

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Asian Chemistry Letters                                                                                    Vol. 16, No. 2 (2012)43-00


Energy calculations of molecular orientation for organic/inorganic hybrid materials containing

metal complexes and azobenzene


Atsuo Yamazaki and Takashiro Akitsu*

Department of Chemistry, Faculty of Science, Tokyo University of Science

1-3Kagurzaka, Shinjuku-ku, Tokyo 162-8601, Japan

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Recently, we have presented an article entitled  “Polarized spectroscopy and polarized UV light-induced molecular  orientation  of chiral diphenyl Schiff base Ni(II) and Cu(II) complexes and azobenzene in a PMMA film  chiroptical properties”  [RSC Advances  2 (2012) 2975]. However, this article contained mainly experimental results and limited discussion based on computational chemistry. In this short note, herein, we describe  detailed results of computation  of  theoretical assumption, computational process, and explanation of differences of Ni(II) and Cu(II) complexes based on energy calculations.

Total Refs : 33

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Asian Chemistry Letters                                                                                    Vol. 16, No. 2 (2012)00-00


Computational UV-VIS and CD spectra of a chiral Schiff base mononuclear Cu(II) complex (salpn)


Atsuo Yamazaki and Takashiro Akitsu*

Department of Chemistry, Faculty of Science, Tokyo University of Science

1-3Kagurzaka, Shinjuku-ku, Tokyo 162-8601, Japan

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We have investigated chriptical properties in the solid states of a chiral salen-type Schiff base mononuclear Cu(II) complex having (S)-2-aminopropane moiety by means of a computational method. In this study, we could elucidate detailed transitions of CD bands as well as spatial distribution of orbitals associated with each transition. In order to interpret exprrimental spectra, we simulated both CD and electronic spectra with TD-DFT calculations. Herein, we report on detailed results of computation of the mononuclear Cu(II) complex as a standard compounds and assignment of transitions as well as bands.

Total Refs : 23

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Asian Chemistry Letters                                                                                    Vol. 16, No. 2 (2012)00-00

 

Schiff base Zn(II) complexes and photochrmic spiropyrans for environmental ion sensing

 

Takatomo Miura, Takashi Onodera, Shinya Endo, Atsuo Yamazaki, and Takashiro Akitsu*

Department of Chemistry, Faculty of Science, Tokyo University of Science

1-3Kagurzaka, Shinjuku-ku, Tokyo 162-8601, Japan

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This is a new photofunctional hybrid system having potential applications for environmental ion sensing. We have prepared several new and known chiral Schiff base Zn(II) complexes and measured (and also calculated) absorption and fluorescence spectra for sole complexes. After assembling hybrid systems with 1,3,3-trimethylindolino-6’-nitrobenzopyrylospiran (SP) in methanol solutions, we measured spectral changes before and after alternate irradiation of UV and visible light. Intensity of fluorescence spectra for pale yellow Zn(II) complexes (lem = 450 nm, lex = 270 and 360 nm) was quenched by colorless SP (lem = 533 nm, lex = 612 nm). After UV light irradiation to form purple merocyanine (MC), photoisomerization resulted in changes of the intensity of absorption spectra as well as fluorescence spectra. Thus the hybrid systems could successfully act as molecular logic circuit by input (excitation by light) and output (intensity of fluorescence peaks). Moreover, we investigated concentration dependence of doped Zn(II) and Cu(II) ions to confirm quenching of intensity of fluorescence peaks by Zn(II) and Cu(II) MC complexes for metal ion sensing in solutions.

Total Refs : 16

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