Platinum complexes photochemistry

For example, in 1963 the photochemistry of magnesium phthalocyanine with coordinated uranium cations was studied in pyridine and ethanol and indicated the occurrence of PET to the uranium complex . A rapid photoinduced electron transfer (2-20 ps) followed by an ultrafast charge recombination was shown for various zinc and magnesium porphyrins linked to a platinum terpyridine acetylide complex . The results indicated the electronic interactions between the porphyrin subunit and the platinum complex, and underscored the potential of the linking para-phenylene bisacetylene bridge to mediate a rapid electron transfer over a long donor-acceptor distance. 

As mechanistic hypothesis it was proposed (9-11) that the excited platinum complex undergoes homolytic Pt Cl cleavage affording a Ptm intermediate and an adsorbed chlorine atom (Scheme 1), by analogy with the known photochemistry of hexachloroplatinate in homogeneous solution (23,31). Electron injection from the platinum(III) complex into the titania conduction band reforms PtIv. Thus, the... 

Platinum(ni).—Unlike the photochemistry of [PtXg] " (X = Br or I) in which only photoaquation is observed,flash photolysis of [PtClsV" in its Cl Pt charge-transfer band has been shown to result also in photoreduction. The unusual Pt" complex [PtC ]" is produced via the mechanism... 

Photochemistry of Oxalate and Dithiooxalate Complexes of Nickel, Palladium, and Platinum... 

In the sections which follow, the principles discussed above will be used in exploring the properties of a range of platinum(II) complexes. The emphasis of the chapter will be on emission—luminescence—from Pt(II) complexes, on the features and properties of molecules that tend to favor emission over other non-radiative processes. In other words, photophysics, as opposed to photochemistry, is our main subject here, but we also consider other excited state processes in selected systems, such as electron transfer and photooxidation. 

The long lifetimes of CT excited states of the Pt(diimine)(dithiolate) complexes allow for bimolecular photochemistry, often involving oxidation of the complex. The earliest report of photoreactivity of these complexes dealt with the photooxidation of Pt(bpy)(tdt) (20) following excitation at 577 nm in chloroform (118). The reaction proceeds with a quantum yield of < ) = 0.03 and was attributed to ET to the halocarbon solvent (Eq. 8) similar to the CTTS photooxidation chemistry of the platinum bis(dithiolate) dianions described above. 

The proposed mechanism of the reaction involves electron transfer from an arene to a platinum(IV) compound to give an intermediate ion-radical pair, [ArH]" [Pt Clj 1 or [ArH]" lPt CU(H20r] (Scheme VII.9) (for the photochemistry of PtCU ", see, e.g., [50]). The route to this ion-radical pair may be conceived ether as an electron transfer within the 7t-complex of ArH with PtCU (VII-15) or PtCU(H20) (VII-16), or as an outer-sphere electron transfer to the excited complex of platinum(IV) with participation of a chlorine ligand (the transformation of strnctnre VII-17 into strnctures VII-18 or VII-19). Subsequent extrusion of Cl from structure VII-20 gives rise to the same ion-radical pair [ArH]" fPt Cl/ ]. 

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