The intercalation of fac-[(4,4′-bpy)Re^I(CO)₃(dppz)]⁺ (dppz = dipyridyl[3,2-a:2′3′-c]phenazine) in polynucleotides, poly[dAdT]₂ and poly[dGdC]₂, where A = adenine, G = guanine, C = cytosine and T = thymine, is a major cause of changes in the absorption and emission spectra of the complex. A strong complex–poly[dAdT]₂ interaction drives the intercalation process, which has a binding constant, K_b ∼ 1.8 × 10⁵ M⁻¹. Pulse radiolysis was used for a study of the redox reactions of e⁻ _aq, C˙H₂OH and N₃˙ radicals with the intercalated complex. These radicals exhibited more affinity for the intercalated complex than for the bases. Ligand-radical complexes, fac-[(4,4′-bpy˙)Re^I(CO)₃(dppz)] and fac-[(4,4′-bpy)Re^I(CO)₃(dppz˙)], were produced by e⁻ _aq and C˙H₂OH, respectively. A Re(II) species, fac-[(4,4′-bpy)Re^II(CO)₃(dppz)]²⁺, was produced by N₃˙ radicals. The rate of annihilation of the ligand-radical species was second order on the concentration of ligand-radical while the disappearance of the Re(II) complex induced the oxidative cleavage of the polynucleotide strand.

Charge separation and charge transfer across interfaces are key aspects in the design of efficient photocatalysts for solar energy conversion. In this study, we investigate the hydrogen generating capabilities and underlying photophysics of nanostructured photocatalysts based on CdSe nanowires (NWs). Systems studied include CdSe, CdSe/CdS core/shell nanowires and their Pt nanoparticle-decorated counterparts. Femtosecond transient differential absorption measurements reveal how semiconductor/semiconductor and metal/semiconductor heterojunctions affect the charge separation and hydrogen generation efficiencies of these hybrid photocatalysts. In turn, we unravel the role of surface passivation, charge separation at semiconductor interfaces and charge transfer to metal co-catalysts in determining photocatalytic H₂ generation efficiencies. This allows us to rationalize why Pt nanoparticle decorated CdSe/CdS NWs, a double heterojunction system, performs best with H₂ generation rates of ∼434.29 ± 27.40 μmol h⁻¹ g⁻¹ under UV/Visible irradiation. In particular, we conclude that the CdS shell of this double heterojunction system serves two purposes. The first is to passivate CdSe NW surface defects, leading to long-lived charges at the CdSe/CdS interface capable of carrying out reduction chemistries. Upon photoexcitation, we also find that CdS selectively injects charges into Pt NPs, enabling simultaneous reduction chemistries at the Pt NP/solvent interface. Pt nanoparticle decorated CdSe/CdS NWs thus enable reduction chemistries at not one, but rather two interfaces, taking advantage of each junction's optimal catalytic activities.

Recent contributions to the chemistry of macrocyclic metal complexes and ligands are reviewed. The compounds reviewed have the following structural features: aza-macrocycles having 1,10-phenanthroline and 2,2′-bipyridine groups and pendants arms; highly aromatic aza-macrocycles with phthalocyanine and porphyrin units incorporating pendant arms; aliphatic aza-macrocycles with pendant arms and/or polynucleating aza-macrocycles. Several of their chemical properties are critically reviewed but the emphasis is on structural and synthetic details.