TY - JOUR
T1 - Cooperative Excited-State Behavior in Platinum (II) Magnus-Type Double-Salt Materials. Active and Inactive Photosensitizers for H2 Production in Aqueous Suspension
AU - Houlding, Virginia H.
AU - Frank, Arthur J.
PY - 1985/10/1
Y1 - 1985/10/1
N2 - Diffuse-reflectance and emission behavior are used to characterize the lowest excited state of the following [PtII]2+[PtII]2- double salts and in some cases their hydrates: [Pt(NH3)4][PtCl4] (MGS), [Pt(bpy)2] [PtCl4] (PB(C1); bpy = 2,2'-bipyridine), [Pt-(bpy)(MHB)][PtCl4] (PHB(Cl); MHB = 4-methyl-4'-heptyl-2,2'-bipyridine), [Pt(bpy)2][Pt(CN)4] (PBC), and [Pt(bpy)-(MHB)] [Pt(CN)4] (PHBC). All of the salts containing the PtCl42- anion have lowest excited states of the ligand field type. In green MGS, where metal-metal interaction is significant, no emission occurs, but in yellow PB(Cl)·2.5H2O and PHB(Cl), where interaction is weak, emission characteristic of PtCl42- is observed. In orange PBC·2H2O and PHBC·2.5H2O and their red anhydrates, the lowest excited state is assigned as a delocalized 3Pt(5dz2-6pz) state. Both salts exhibit strong emission (in PBC powder at room temperature, the emission quantum yield is 0.002 ± 0.001 and the lifetime is 16.8 ± 2.5 ns), which overlaps well with an intense visible absorption band. PBC and PHBC powders are active as photosensitizers for the reduction of water in EDTA solutions. In the presence of Pt(0) catalyst, H2 production is sustained at a constant rate to >1 turnover with respect to photosensitizer, with no evidence for photosensitizer degradation. In the absence of Pt(0), PBC produces H2 at a constant rate that is less than 1% of the rate in the presence of Pt(0), but again, without degradation. MGS, PB(Cl), and PHB(Cl) are photoinert and completely inactive as photosensitizers in this reaction. These results are interpreted in terms of the cooperative excited-state structure of these materials.
AB - Diffuse-reflectance and emission behavior are used to characterize the lowest excited state of the following [PtII]2+[PtII]2- double salts and in some cases their hydrates: [Pt(NH3)4][PtCl4] (MGS), [Pt(bpy)2] [PtCl4] (PB(C1); bpy = 2,2'-bipyridine), [Pt-(bpy)(MHB)][PtCl4] (PHB(Cl); MHB = 4-methyl-4'-heptyl-2,2'-bipyridine), [Pt(bpy)2][Pt(CN)4] (PBC), and [Pt(bpy)-(MHB)] [Pt(CN)4] (PHBC). All of the salts containing the PtCl42- anion have lowest excited states of the ligand field type. In green MGS, where metal-metal interaction is significant, no emission occurs, but in yellow PB(Cl)·2.5H2O and PHB(Cl), where interaction is weak, emission characteristic of PtCl42- is observed. In orange PBC·2H2O and PHBC·2.5H2O and their red anhydrates, the lowest excited state is assigned as a delocalized 3Pt(5dz2-6pz) state. Both salts exhibit strong emission (in PBC powder at room temperature, the emission quantum yield is 0.002 ± 0.001 and the lifetime is 16.8 ± 2.5 ns), which overlaps well with an intense visible absorption band. PBC and PHBC powders are active as photosensitizers for the reduction of water in EDTA solutions. In the presence of Pt(0) catalyst, H2 production is sustained at a constant rate to >1 turnover with respect to photosensitizer, with no evidence for photosensitizer degradation. In the absence of Pt(0), PBC produces H2 at a constant rate that is less than 1% of the rate in the presence of Pt(0), but again, without degradation. MGS, PB(Cl), and PHB(Cl) are photoinert and completely inactive as photosensitizers in this reaction. These results are interpreted in terms of the cooperative excited-state structure of these materials.
UR - http://www.scopus.com/inward/record.url?scp=0001618380&partnerID=8YFLogxK
U2 - 10.1021/ic00216a038
DO - 10.1021/ic00216a038
M3 - Article
AN - SCOPUS:0001618380
SN - 0020-1669
VL - 24
SP - 3664
EP - 3668
JO - Inorganic Chemistry
JF - Inorganic Chemistry
IS - 22
ER -