ABSTRACT
Gold nanorods (GNRs) were encapsulated and dispersed into organic solvents by tetrabenzylthiol resorcinarene (TBTR) and by a poly(dithiocarbamate) derived from tetra- N-methyl(aminomethyl)resorcinarene (TMAR-DTC), formed by the in situ condensation of TMAR with carbon disulfide. The latter proved to be highly effective at enabling the redispersion of GNRs in various organic solvents. GNRs encapsulated in TMAR-DTC exhibited a strong solvatochromic response, with a refractive index sensitivity of over 300 nm/RIU. The resorcinarene-encapsulated GNRs could withstand high temperatures for a short period of time, and could be used to nucleate the growth of magnetic nanoshells.
ABSTRACT
Spectroscopic and electrochemical characterizations of ferrocene- and biferrocene-functionalized terpyridine octanethiolate monolayer-protected clusters were investigated and reported. The electrochemical measurements of Ru2+ coordinated with 4'-ferrocenyl-2,2':6',2' '-terpyridine and 4'-biferrocenyl-2,2':6',2' '-terpyridine complexes were dominated by the Ru2+/Ru3+ redox couple (E(1/2) at approximately 1.3 V), Fe(2+)/Fe(3+) redox couples (E(1/2) from approximately 0.6 to approximately 0.9 V), and terpy/terpy-/terpy2- redox couples (E(1/)(2) at ca. -1.2 and ca. -1.4 V). The substantial appreciable variations detected in the Ru2+/Ru3+ and Fe2+/Fe3+ oxidation potentials indicate that there is an interaction between the Ru2+ and Fe2+ metal centers. The coordination of the Ru2+ metal center with 4'-ferrocenyl-2,2':6',2' '-terpyridine and 4'-biferrocenyl-2,2':6',2' '-terpyridine leads to an intense 1[(d(pi)Fe)6] --> 1[d(pi)Fe)5(pi*terpyRu)1] transition in the visible region. The 1[(d(pi)Fe)6] -->1[d(pi)Fe)5(pi*terpyRu)1] transition observed at approximately 510 nm revealed that there was a qualitative electronic coupling between metal centers. The coordination of the Ru2+ transition metal center lowers the energy of the pi*terpy orbitals, causing this transition.
Subject(s)
Ferrous Compounds/chemistry , Gold/chemistry , Organometallic Compounds/chemical synthesis , Pyridines/chemistry , Ruthenium/chemistry , Electrochemistry , Metallocenes , Molecular Structure , Organometallic Compounds/chemistry , Oxidation-Reduction , Particle Size , Surface PropertiesABSTRACT
The spectroscopic and electrochemical characterizations of electrochemically stable biferrocene-modified Au clusters and chemisorbed biferrocenylalkanethiols on Au(111) surface were studied. The characterizations of biferrocene-modified Au cluster using TEM, UV-vis, and NMR techniques are also reported. Two successive reversible one-electron redox waves were observed for the biferrocenylalkanethiol Au nanoclusters and biferrocenylalkanethiol monolayers on Au(111) surface in the cyclic voltammetry. Furthermore, the positive and negative current peaks for each redox wave occur at almost the same potential, and the peak current increases almost linearly with the sweep rate. Repeat scanning does not change the voltammograms, demonstrating that these monolayers are stable to electrochemical cycling. The coverages of electroactive biferrocene in the monolayers were calculated from the cyclic voltammograms. The standard electron-transfer rate constant was calculated from the splitting between the oxidation and reduction peaks.
