Photochemistry of iodoform in methanol: Formation and fate of the iso-CHI2-I photoproduct

Patrick Z. El-Khoury; Wai Ming Kwok; Xiangguo Guan; Chensheng Ma; David Lee Phillips; Alexander N. Tarnovsky

doi:10.1002/cphc.200900122

Photochemistry of iodoform in methanol: Formation and fate of the iso-CHI₂-I photoproduct

Patrick Z. El-Khoury, Wai Ming Kwok, Xiangguo Guan, Chensheng Ma, David Lee Phillips, Alexander N. Tarnovsky

Research output: Journal article publication › Journal article › Academic research › peer-review

30 Citations (Scopus)

Abstract

Ultrafast population and structural dynamics due to the iso-CHI 2-I isomer product formed upon UV excitation of iodoform (CHI 3) in solution is monitored by femtosecond transient absorption with deep-UV through near-IR probing and picosecond transient resonance Raman spectroscopy. Iso-CHI2-I is found to be a major photochemical product regardless of excitation wavelength (266 and 350 nm) and choice of solvent (methanol, acetonitrile, and cyclohexane), and is produced in 50% quantum yield upon 266 nm excitation of CHI3 in CH3OH. The isomer remains stable up to at least several nanoseconds in C6H12 and CH3CN, but undergoes decay with a 740 ps lifetime in CH 3OH simultaneously with the formation of an iodide ion. In agreement with the experiments, MP2 calculations suggest that iso-CHI2-I readily reacts with CH3OH via O-H insertion/HI elimination reactions. KGaA, Weinheim.

Original language	English
Pages (from-to)	1895-1900
Number of pages	6
Journal	ChemPhysChem
Volume	10
Issue number	11
DOIs	https://doi.org/10.1002/cphc.200900122
Publication status	Published - 3 Aug 2009

Keywords

Density functional calculations
Iodoform
Isomerization
Photochemistry
Solvent effects

ASJC Scopus subject areas

Atomic and Molecular Physics, and Optics
Physical and Theoretical Chemistry

More information

10.1002/cphc.200900122

Cite this

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title = "Photochemistry of iodoform in methanol: Formation and fate of the iso-CHI2-I photoproduct",

abstract = "Ultrafast population and structural dynamics due to the iso-CHI 2-I isomer product formed upon UV excitation of iodoform (CHI 3) in solution is monitored by femtosecond transient absorption with deep-UV through near-IR probing and picosecond transient resonance Raman spectroscopy. Iso-CHI2-I is found to be a major photochemical product regardless of excitation wavelength (266 and 350 nm) and choice of solvent (methanol, acetonitrile, and cyclohexane), and is produced in 50% quantum yield upon 266 nm excitation of CHI3 in CH3OH. The isomer remains stable up to at least several nanoseconds in C6H12 and CH3CN, but undergoes decay with a 740 ps lifetime in CH 3OH simultaneously with the formation of an iodide ion. In agreement with the experiments, MP2 calculations suggest that iso-CHI2-I readily reacts with CH3OH via O-H insertion/HI elimination reactions. KGaA, Weinheim.",

keywords = "Density functional calculations, Iodoform, Isomerization, Photochemistry, Solvent effects",

author = "El-Khoury, {Patrick Z.} and Kwok, {Wai Ming} and Xiangguo Guan and Chensheng Ma and Phillips, {David Lee} and Tarnovsky, {Alexander N.}",

year = "2009",

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T1 - Photochemistry of iodoform in methanol: Formation and fate of the iso-CHI2-I photoproduct

AU - El-Khoury, Patrick Z.

AU - Kwok, Wai Ming

AU - Guan, Xiangguo

AU - Ma, Chensheng

AU - Phillips, David Lee

AU - Tarnovsky, Alexander N.

PY - 2009/8/3

Y1 - 2009/8/3

N2 - Ultrafast population and structural dynamics due to the iso-CHI 2-I isomer product formed upon UV excitation of iodoform (CHI 3) in solution is monitored by femtosecond transient absorption with deep-UV through near-IR probing and picosecond transient resonance Raman spectroscopy. Iso-CHI2-I is found to be a major photochemical product regardless of excitation wavelength (266 and 350 nm) and choice of solvent (methanol, acetonitrile, and cyclohexane), and is produced in 50% quantum yield upon 266 nm excitation of CHI3 in CH3OH. The isomer remains stable up to at least several nanoseconds in C6H12 and CH3CN, but undergoes decay with a 740 ps lifetime in CH 3OH simultaneously with the formation of an iodide ion. In agreement with the experiments, MP2 calculations suggest that iso-CHI2-I readily reacts with CH3OH via O-H insertion/HI elimination reactions. KGaA, Weinheim.

AB - Ultrafast population and structural dynamics due to the iso-CHI 2-I isomer product formed upon UV excitation of iodoform (CHI 3) in solution is monitored by femtosecond transient absorption with deep-UV through near-IR probing and picosecond transient resonance Raman spectroscopy. Iso-CHI2-I is found to be a major photochemical product regardless of excitation wavelength (266 and 350 nm) and choice of solvent (methanol, acetonitrile, and cyclohexane), and is produced in 50% quantum yield upon 266 nm excitation of CHI3 in CH3OH. The isomer remains stable up to at least several nanoseconds in C6H12 and CH3CN, but undergoes decay with a 740 ps lifetime in CH 3OH simultaneously with the formation of an iodide ion. In agreement with the experiments, MP2 calculations suggest that iso-CHI2-I readily reacts with CH3OH via O-H insertion/HI elimination reactions. KGaA, Weinheim.

KW - Density functional calculations

KW - Iodoform

KW - Isomerization

KW - Photochemistry

KW - Solvent effects

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