The kinetics of the α-PcCu →β- PcCu conversion in air has been followed, under isothermal conditions, in situ real-time in the 423-443 K temperature range. Data have been fitted following the JMAK model. The reaction order of the kinetics at 423 K is consistent with a diffusion controlled, deceleratory nucleation rate process for 2D laminar particles, whereas at higher temperatures it is consistent with a phase boundary controlled, deceleratory nucleation rate process for 2D laminar particles. At 423 K, the overall transformation mechanism implies three steps: growth of the α-PcCu phase, disordering of adjacent columns of molecules of phthalocyanine, and nucleation and growth of the β-PcCu phase. The calculated empirical activation energy is of 187 kJ/mol significantly greater than that for the α-PcCo →β- PcCo conversion. This fact seems to support the reported different structures of α-PcCo and a-PcCu. Investigation of the thermal behavior of β-PcCu indicates a strongly anisotropic thermal expansion that follows the αc » αa ≈ αb trend. Moreover, the β angle decreases with increasing temperature. Such anisotropy is consistent with the geometry of the very weak N3...H3 hydrogen bond which acts mainly along the c axis. © 2009 American Chemical Society.

Kinetics of α-PcCu → β-PcCu isothermal conversion in air and thermal behavior of β-PcCu from in situ real-time laboratory parallel-beam X-ray powder diffraction / Ballirano, Paolo; Caminiti, Ruggero. - In: JOURNAL OF PHYSICAL CHEMISTRY. A, MOLECULES, SPECTROSCOPY, KINETICS, ENVIRONMENT, & GENERAL THEORY. - ISSN 1089-5639. - STAMPA. - 113:27(2009), pp. 7774-7778. [10.1021/jp902903d]

Kinetics of α-PcCu → β-PcCu isothermal conversion in air and thermal behavior of β-PcCu from in situ real-time laboratory parallel-beam X-ray powder diffraction

BALLIRANO, Paolo;CAMINITI, Ruggero
2009

Abstract

The kinetics of the α-PcCu →β- PcCu conversion in air has been followed, under isothermal conditions, in situ real-time in the 423-443 K temperature range. Data have been fitted following the JMAK model. The reaction order of the kinetics at 423 K is consistent with a diffusion controlled, deceleratory nucleation rate process for 2D laminar particles, whereas at higher temperatures it is consistent with a phase boundary controlled, deceleratory nucleation rate process for 2D laminar particles. At 423 K, the overall transformation mechanism implies three steps: growth of the α-PcCu phase, disordering of adjacent columns of molecules of phthalocyanine, and nucleation and growth of the β-PcCu phase. The calculated empirical activation energy is of 187 kJ/mol significantly greater than that for the α-PcCo →β- PcCo conversion. This fact seems to support the reported different structures of α-PcCo and a-PcCu. Investigation of the thermal behavior of β-PcCu indicates a strongly anisotropic thermal expansion that follows the αc » αa ≈ αb trend. Moreover, the β angle decreases with increasing temperature. Such anisotropy is consistent with the geometry of the very weak N3...H3 hydrogen bond which acts mainly along the c axis. © 2009 American Chemical Society.
2009
01 Pubblicazione su rivista::01a Articolo in rivista
Kinetics of α-PcCu → β-PcCu isothermal conversion in air and thermal behavior of β-PcCu from in situ real-time laboratory parallel-beam X-ray powder diffraction / Ballirano, Paolo; Caminiti, Ruggero. - In: JOURNAL OF PHYSICAL CHEMISTRY. A, MOLECULES, SPECTROSCOPY, KINETICS, ENVIRONMENT, & GENERAL THEORY. - ISSN 1089-5639. - STAMPA. - 113:27(2009), pp. 7774-7778. [10.1021/jp902903d]
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11573/230478
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