Evidence of photoinduced charge separation in the metal-organic framework MIL-125(Ti)-NH2.
Herein, we describe the photochemical behavior of the porous metal-organic framework MIL-125(Ti)-NH(2), built up from cyclic Ti(8)O(8)(OH)(4) oxoclusters and 2-aminoterephthalate ligands. While MIL-125(Ti)-NH(2) does not emit upon excitation at 420 nm, laser flash photolyses of dry samples (diffuse reflectance) or aqueous suspensions (transmission) of the solid have allowed detecting a transient characterized by a continuous absorption from 390 to 820 nm decaying in the sub-millisecond timescale, which is quenched by oxygen. This transient has been attributed to the charge-separation state. Firm evidence for this assignment was obtained by lamp irradiation of aqueous suspensions of MIL-125(Ti)-NH(2) in the presence of electron-donor (N,N,N'N'-tetramethyl-p-phenylenediamine) or electron-acceptor (methylviologen) probe molecules, which has allowed the visual detection of the corresponding radical ions, in agreement with the occurrence of photoinduced charge separation in MIL-125(Ti)-NH(2).
Instituto de Tecnología Química CSIC-UPV, Universidad Politécnica de Valencia, Spain.
Maykel
M
de Miguel
Florence
F
Ragon
Thomas
T
Devic
Christian
C
Serre
Patricia
P
Horcajada
Hermenegildo
H
García
D000588:Amines / Q000737:chemistry*; D003500:Cyclization; D008027:Light; D008958:Models, Molecular; D009942:Organometallic Compounds / Q000737:chemistry*; D010100:Oxygen / Q000737:chemistry*; D055668:Photochemical Processes; D010795:Phthalic Acids / Q000737:chemistry*; D016062:Porosity; D012666:Semiconductors; D014025:Titanium / Q000737:chemistry*
D000588:Amines; D009942:Organometallic Compounds; D010795:Phthalic Acids; D014025:Titanium; D010100:Oxygen