Evaluation of a Hot Print System for the development of latent fingermarks on thermal paper: A pseudo-operational trial.

Enhancement of latent fingermarks on thermal paper poses a number of problems when using traditional methods used for porous substrates due to blackening of the thermal layer as a result of polar solvents present within the reagents and high temperatures oxidising the acid/dye complex. Thus, methods which prevent such reactions are favoured for the development of latent prints on said substrates. A comparative pseudo-operational trial using UV, Hot Print System (HPS), ninhydrin and ThermaNIN was performed on 1000 thermal paper substrates gathered from various sources. The results indicated that the most effective method was an acetone pre-wash followed by ninhydrin. The sequence of HPS-ninhydrin was similarly effective when compared to ninhydrin as a sole technique. ThermaNIN produced fewer marks than ninhydrin but was superior to HPS. Whilst the HPS developed some fingermarks, there was only a very small number of marks uniquely developed by it.

Self-assembly of a heteroleptic one-dimensional chain comprising different dinuclear meso-helicates in the solid-state.

We describe two mesocate assemblies that contain either an ethylene glycol or ammonium group which form a heteroleptic one-dimensional infinite chain in the solid state.

Steric control of the formation of dinuclear double helicate and dinuclear meso-helicate assemblies.

We describe a ligand system that forms either a dinuclear double helicate or a dinuclear double mesocate dependent upon the size of the metal ion or the steric bulk of the ligand strand.

Diastereoselective assembly of pentanuclear circular helicates.

Reaction of a ligand which contains two N-donor and O-donor tridentate domains separated by a 1,3-phenylene spacer unit with Zn(2+) ions results in a pentanuclear circular helicate [Zn(5)(L)(5)](10+) and this structure persists in both the solid and solution state. The formation of this high nuclearity species is governed by unfavourable steric interactions between the phenyl units which destabilize the simple linear helicate. Incorporation of enantiopure units within the ligand strand controls the diastereoselectivity with up to 80% d.e.

Coumarin-based luminescent ligand that forms helicates with dicationic metal ions.

The potentially hexadentate ligand L, which contains two terminal coumarin fluorophores, forms dinuclear double-stranded helicates with dicationic metal ions, giving species of the generic form [M(2)L(2)](4+). In solution the free ligand was fluorescent with emission attributed to the coumarin fluorophores (lambda(em) = 437 nm). The luminescent properties of the corresponding dimetallic helicates complexes were examined and revealed that the Zn(2+) complex demonstrates enhanced emission when compared to the parent ligand, whereas Co(2+), Cu(2+), Cd(2+) and Hg(2+) induce varying degrees of fluorescence quenching. In particular, comparative luminescence measurements at 77 K and room temperature showed that the quenching mechanism for [Cu(2)L(2)](4+) can be attributed to a photoinduced electron transfer. ESI-MS selectivity studies showed that in the presence of a mixture of metal dications no preference for any one metal ion was observed.