Quenching of singlet molecular oxygen ( sup 1. Delta. sub g O sub 2 ) in silica gel/cyclohexane heterogeneous systems. A direct time-resolved study

Journal Article · Wed Apr 25 00:00:00 EDT 1990 · Journal of the American Chemical Society; (USA)

DOI:https://doi.org/10.1021/ja00165a010· OSTI ID:6620073

Iu, Kaikong; Thomas, J K ^[1]

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1. Univ. of Notre Dame, IN (USA)

Direct time-resolved studies of singlet molecular oxygen ({sup 1}{Delta}{sub g}O{sub 2}) phosphorescence ({sup 3}{Sigma}{sub g} {sup {minus}}O{sub 2} ({nu} = 0) {l arrow} {sup 1}{Delta}{sub g}O{sub 2} ({nu} = 0); 1,270 nm) in heterogeneous silica gel/cyclohexane systems are presented. Singlet molecular oxygen ({sup 1}{Delta}{sub g}O{sub 2}) is created through a photosensitization process on silica gel surfaces. The experimental results show that the lifetimes of singlet molecular oxygen ({sup 1}{Delta}{sub g}O{sub 2}) in both porous and compressed fumed silica/gel cyclohexane systems are significantly less than that in liquid cyclohexane. The shortened singlet molecular oxygen lifetime is due mainly to quenching by adsorbed water and silanol groups on the silica gel surface. In addition, monoamines coadsorbed on the silica gel surface do not quench singlet molecular oxygen ({sup 1}{Delta}{sub g}O{sub 2}); however, diamines such as DABCO or piperazine maintain their quenching activity, but the quenching kinetics are not of the Stern-Volmer type. The singlet molecular oxygen lifetime increases on loading the porous silica gel/cyclohexane system with monoamine. Coadsorption of piperazine increases quenching of {sup 1}{Delta}{sub g} O{sub 2} by DABCO.

• OSTI ID: 6620073
• Journal Information: Journal of the American Chemical Society; (USA), Journal Name: Journal of the American Chemical Society; (USA) Vol. 112:9; ISSN 0002-7863; ISSN JACSA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
ADSORBENTS
CATALYSIS
DATA
DATA ANALYSIS
ELEMENTS
EXPERIMENTAL DATA
INFORMATION
MEASURING INSTRUMENTS
MEASURING METHODS
NONMETALS
NUMERICAL DATA
OXYGEN
QUENCHING
SILICA GEL