Synthesis and Crystal Structure of Platinum Blue [(1,10-phen)Pt(μ-NHCOCH3)2Pt(1,10-phen)]2(NO3)4

From Single Pt Atoms to Pt Nanocrystals: Photoreduction of Pt2+ Inside of a PAMAM Dendrimer

“…The intense bands at 260 and 290 nm have been assigned to a ligand-to-metal electron-transition n → d* from N into a Pt cation in mono- and polynuclear Pt complexes. In Pt–PAMAM, the ratio of intensities for 290 and 490 nm bands is 1/(2 – 4) × 10 –2 , which is in a good agreement with the data for charge-transfer (274 nm) and d–d* (480 nm) bands for individual Pt-blue tetranuclear complexes . XPS measurements show a change in the Pt electronic state after photoreduction of Pt–PAMAM.…”

Spectroscopic Study of Platinum and Rhodium Dendrimer (PAMAM G4OH) Compounds: Structure and Stability

“…Reduction of Pt 2+ cations supported on or in the dendrimer by BH 4 − or by H 2 is described by eq false( Pt 2 + false) italicn normalG 4 OH → BH 4 − / normalH 2 false( Pt 2 + false) normalG 4 OH + false( Pt 2 + false) 2 normalG 4 OH + false( Pt 0 false) italicm normalG 4 OH The results from several experimental techniques support this hypothesis. For example a large amount of mononuclear Pt 2+ remaining after NaBH 4 reduction has been shown by UV−vis spectroscopy and present work, XPS spectroscopy , and Raman spectroscopy (present work), and a small amount of Pt 2+ −Pt 2+ (and tetramers) by EXAFS and UV-spectroscopy [ ref and present work]. The presence of Pt-colloids was detected by TEM, XPS, , and EXAFS …”

“…A new band appears in the spectrum near 290 nm (Figure c), which may be assigned to charge transfer transition to a vacant d orbital of platinum(II) multinuclear clusters. Formation of binuclear and tetranuclear “platinum blue” compounds may induce a red shift of the CT band . The presence of the new band is more evident in the inset in Figure c.…”

“…Inside the dendrimer, a minute quantity of Pt 2+ small clusters with 2−4 Pt 2+ atoms are formed by reduction of (Pt 2+ ) n G4OH, and other platinum ions are left unaffected, as detected by EXAFS . Such small clusters of platinum coordinated to nondendrimeric amide ligands (“platinum blue”) have been isolated and structurally characterized, and it is known that the (Pt δ+ ) n cluster, where n = 2, 4, has characteristic absorption bands at 290−300 nm and 347−375 nm . We attribute the new band in our spectra at 290 nm to binuclear Pt 2+ − Pt 2+ or tetranuclear Pt 4 linear clusters stabilized by amide bridging ligands, as in the so-called “platinum blue” coordination compounds.…”

“…In the background-corrected spectrum three bands may be perceived at 214 nm, 266 and 300 nm (Figure b). We assume that the band at 266 nm can be assigned to the CT n*→d transition for unreduced Pt 2+ and the two other new bands can be attributed to Pt clusters formed by the aggregation of two or four Pt ions . The band at 300 nm can be assigned to charge transfer of electrons from the stabilizer to the Pt atoms of the cluster.…”