The design of multinuclear metal complexes requires a match of the ligand-to-metal vectors and the preferred coordination geometries of the metal ions. Only a few ligands are known with a parallel orientation of N→M vectors that brings the metal ions into close proximity. We establish here the adenine derivative 1,N(6)-ethenoadenine (εA) as an ideal bis(monodentate) ligand. Scanning tunneling microscope images of alkylated εA on graphite surface clearly indicate that these ligands bind to Ag(I) ions. The molecular structures of [Ag2(1)2](ClO4)2 and [Ag2(2)2](ClO4)2 (1, 9-ethyl-1,N(6)-ethenoadenine; 2, 9-propyl-1,N(6)-propylenoadenine) confirm that dinuclear complexes with short Ag···Ag distances are formed (3.0256(3) and 2.984(1) Å, respectively). The structural motif can be extended to divalent metal ions, as was shown by determining the molecular structure of [Cu2(1)2(CHO2)2(OH2)2](NO3)2·2H2O with a Cu···Cu distance of 3.162(2) Å. Moreover, when introducing the 1,N(6)-ethenoadenine deoxyribonucleoside into parallel-stranded DNA duplexes, even dinuclear Ag(I)-mediated base pairs are formed, featuring the same transoid orientation of the glycosidic bonds as the model complexes. Hence, 1,N(6)-ethenoadenine and its derivatives are ideally suited as bis(monodentate) ligands with a parallel alignment of the N→M vectors for the construction of supramolecular metal complexes that require two metal ions at close distance.

This communication explores the effect of varying substituent bulk at the N9 position of the adenine moiety and its effect in dictating the structural aspects of silver-adenine frameworks. While adenine alone or 9-benzyl substituted ligand afforded mono and dinuclear dimeric entities, n-propyl substitution at the N9 position results in the formation of a metallaquartet. Longer n-alkyl chains (hexyl and nonyl) resulted in the formation of linear polymeric chains, via N1 and N7 coordination.

Cadmium sulfide (CdS)-decorated, cross-linked melamine–formaldehyde polymer-based nanocomposite (MFP-CdS) has been synthesized. MFP-CdS is utilized here as a photoactive material for the photodegradation of six model organic dyes and their mixture in an aqueous medium in the presence of sunlight. The half-life values from the kinetic study of multiple dyes strongly support the importance of sunlight on the fast degradation of all six dyes compared to bulb light and control (dark) conditions. A comparative 1H NMR analysis of the dyes and their degraded products has been performed to support the breakdown of the aromatic framework of organic dyes using MFP-CdS in sunlight. The mechanisms involved in the photodegradation of dyes have been investigated based on radical trapping studies that support the significant involvement of superoxide radicals along with holes. Moreover, the dye removal efficiency using MFP-CdS from real industrial wastewater samples is evaluated via the external spiking of organic dyes and their mixture in unknown industrial effluents where they showed similar photodegradation results. Based on the high recyclability of MFP-CdS, these are used for multiple cycles.

This Communication describes the synthesis and crystallographic investigation of copper(I) and silver(I) complexes of a modified adenine analogue, bearing a thiocyanate pendant arm at the N9 position. A novel adenine-containing hexagonal prismatic cuprous iodide aggregate was obtained with Cu(+), while Ag(+) interaction afforded interconnected two- and four-membered metallacycles.

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