Spectroscopic investigation on the photoinduced charge-transfer between ferrocene and chloroform molecules confined in a poly(methyl methacrylate) thin film

Thander, Alfazuddin; Mallik, Biswanath

doi:10.1016/s0038-1098(99)00181-7

Cited by 14 publications

(8 citation statements)

References 12 publications

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“…In addition, the photooxidation of ferrocene in PMMA film in the presence of chloroform molecules has shown enhanced photoconductivity [ 49 ]. Similar to our observation [ 38 , 39 ] on photooxidation of ferrocene in the presence of chloroform molecules confined in the PMMA thin film, Cyr et. al.…”

Section: Resultssupporting

confidence: 93%

“…From eqn.2, one can estimate the value of ionization potential/ energy of donor-2 if the ionization potential/ energy of the donor-1 and the associated values of the υ CT are known. We have estimated the values of the ionization energy of ruthenocene from eqn.2 by assuming I D (donor-1) to be 6.88 eV for ferrocene [ 42 ] and considering the CT band for ferrocene-chloroform complex [ 38 ] at 315 nm (hυ CT (1) = 3.93 eV). The consideration of the CT band for the ruthenocene-chloroform complex formed without photoexcitation, at 281 nm (hυ CT (2) = 4.41 eV), and at 285 nm (hυ CT (2)= 4.35 eV) for ruthenocene-chloroform complex formed after photoexcitation in the PMMA film gives the estimated value of ionization energy of ruthenocene as 7.36 and 7.30 eV, respectively.…”

Section: Resultsmentioning

confidence: 99%

“…The PMMA film acts as a matrix to hold on the sample and solvent molecules together in the solid phase. Recent studies in our laboratory [ 38 , 39 , 40 ] have shown that photoinduced charge-transfer occurs between metallocenes and chloroform molecules confined in PMMA thin films i.e. photooxidation of metallocenes in the presence of chloroform molecules is possible in the PMMA matrix.…”

Section: Introductionmentioning

confidence: 99%

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Photooxidation of Some Metallocenes in a Polymer Matrix

Mallik

2005

Molecules

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The changes in the electronic absorption spectra (UV-Vis) of some metallocene-doped poly(methyl methacrylate) (PMMA) thin films containing chloroform molecules as impurities were studied after photoexcitation in the nitrogen atmosphere. Photoexcitations were made by monochromatic radiation (using a Xe-lamp source and a monochromator) at an interval of few nanometers in the spectral range 210-750 nm. The changes in spectra were studied as a function of photoexcitation time (duration), amount of metallocene in the film and the amount of chloroform molecules present in the film. Occurrence of photoinduced charge-transfer between some metallocenes and chloroform molecules confined in the PMMA thin films was observed, which indicated photooxidation of the metallocenes in the polymer matrix. Photoresponse in the case of ferrocene derivatives was observed to decrease with the increase in the value of para-Hammett constant for the substituent attached to the ferrocene unit and also with increasing half-wave potential for the ferrocene derivatives. Photoeffects on the metallocenes having different central metal atom were studied and it was noticed that the photoeffects on the metallocenes with "18 valence electrons", as in ferrocene and ruthenocene, favored the occurrence of photoinduced charge-transfer between the metallocene and chloroform molecules present in a PMMA film. The photooxidation of a metallocene in a PMMA thin film resulted in an enhanced photoconductivity of the polymeric film.

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Section: Resultssupporting

confidence: 93%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Photooxidation of Some Metallocenes in a Polymer Matrix

Mallik

2005

Molecules

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“…[22] The charge-transfer to solvent between ferrocenes and CHCl 3 in a PMMA matrix has also been investigated, and photogeneration of the ferrocenium cation was observed. [23,24] The resulting composite material was reported to exhibit photoconductivity. [25] Because of our interest in the electrical properties of ferrocene-containing polymers, we have explored the potential of photooxidation of PFS in the presence of CHCl 3 .…”

Section: Introductionmentioning

confidence: 99%

Photooxidation and Photoconductivity of Polyferrocenylsilane Thin Films

Cyr¹,

Tzolov²,

Manners³

et al. 2003

Macro Chemistry & Physics

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Irradiation of thin films of poly(ferrocenylmethylphenylsilane) ([Fe(η5‐C5H4)2SiMePh]n) cast from chloroform solution with UV light leads to photooxidation of ferrocene centers in the polymer main chain. The extent of the polymer oxidation can be controlled in the range ca. 0–5% by the duration of the irradiation exposure and by the concentration of chloroform. The photooxidized polyferrocenylsilane material is conductive, with an increased conductivity of greater than three orders of magnitude relative to the unoxidized material. In addition, the photooxidized polymers have been found to be photoconductive. The photooxidation process can be reversed by means of chemical reduction using hydrazine or decamethylferrocene, leading to the regeneration of the neutral polymers. However, substantial molecular weight decline was detected during the photooxidation/reduction process, presumably as a result of chain cleavage reactions induced by the anionic or radical chlorinated photoproducts. Methylation of the cyclopentadienyl rings of the ferrocene moiety in the polymer was found to lead to materials which are significantly more stable.Time trace of the current at constant applied voltage of 100 V for a PFS film upon illumination. The ON and OFF states were created by using a mechanical shutter.magnified imageTime trace of the current at constant applied voltage of 100 V for a PFS film upon illumination. The ON and OFF states were created by using a mechanical shutter.

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“…It has wide applications as an inert solid matrix for various spectroscopic [3,4] and optoelectronic [5] investigations as good quality thin films can be prepared easily by solution casting technique. Investigation on the spectroscopic and electrical properties of PMMA films in pure state as well as films containing other organic and organometallic materials has become a subject of recent interest in our laboratory [3]. Such studies are important for searching new type of electrically conducting polymeric systems in the form of thin films.…”

Section: Introductionmentioning

confidence: 99%

Anomalous Behaviour of Electrical Conductivity Observed in Insulating Poly(methyl Methacrylate) Thin Films Cast under Humid Atmosphere

Thander

Bera

Mallik

2002

phys. stat. sol. (a)

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Electrical conductivity of the solution cast thin films of poly(methyl methacrylate) [PMMA] has been studied in the temperature range 290-359 K by using surface-type cells. Anomalous behaviour of electrical conductivity has been observed (during heating as well as cooling) at a particular temperature range higher than room temperature, showing a negative temperature coefficient of electrical conductivity in the thin films of PMMA prepared in a humid atmosphere with relative humidity greater than~90%. DSC measurements on such a thin film suggest the existence of two phase transitions in the film in the studied temperature range. Films prepared in a dry atmosphere or films prepared by incorporating water externally did not show any such anomalous behaviour in conductivity. The results related to anomalous behaviour in electrical conductivity of PMMA films have been discussed.

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Spectroscopic investigation on the photoinduced charge-transfer between ferrocene and chloroform molecules confined in a poly(methyl methacrylate) thin film

Cited by 14 publications

References 12 publications

Photooxidation of Some Metallocenes in a Polymer Matrix

Photooxidation of Some Metallocenes in a Polymer Matrix

Photooxidation and Photoconductivity of Polyferrocenylsilane Thin Films

Anomalous Behaviour of Electrical Conductivity Observed in Insulating Poly(methyl Methacrylate) Thin Films Cast under Humid Atmosphere

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