1,10-Phenanthroline entails several appealing structural and chemical properties: rigidity, planarity, aromaticity, basicity, chelating capability. This makes it a versatile starting material for synthetic organic, inorganic and supramolecular chemistry. In this tutorial review we examine how the chemical versatility of pristine 1,10-phenanthroline, a weakly fluorescent molecule, has been exploited to design many UV-Vis-NIR luminescent organic derivatives and coordination compounds with transition-metal (Ru(II), Os(II), Rh(III), Cr(III), Pt(II), Zn(II), Cu(I), Ag(I)) and rare-earth (Eu(III),Tb(III), Yb(III), Nd(III), Er(III)) cations. They are utilized for many analytical and technological applications.

1,10-Phenanthrolines: versatile building blocks for luminescent molecules, materials and metal complexes

Metal centered ligand field excited states: Their roles in the design and performance of transition metal based photochemical molecular devices

The composition of the mitochondrial DNA (mtDNA) of the fin whale,Balaenoptera physalus, was determined. The length of the molecule is 16,398 bp, and its organization conforms with that of other mammals. The general similarity between the mtDNA of the fin whale and the cow is greater than the similarity between the fin whale and other species (human, mouse, rat) in which the composition of the entire molecule has been described. The D-loop region of the mtDNA of the fin whale is 81% identical to the D-loop of dolphin DNA, and the central portion of the D-loop is similar to the bovine D-loop. The accumulation of transversions and gaps in the 12S and 16S rRNA genes was assessed by comparing the fin whale, cow, and human. The sequence difference between human and the whale and human and the cow was at the same level, indicating that the rate of evolution of the mtDNA rRNA genes is about the same in artiodactyls and cetaceans. In the 12S rRNA gene an accumulation rate of 0.05% per million years places the separation of cetaceans and artiodactyls at about 55 million years ago. The corresponding figure for human and either the whale or the cow is about 80 million years. In the 16S rRNA gene a 0.08% accumulation rate of transversions and gaps per million years yields concurring figures. A comparison between the cytochromeb gene of the fin whale and cytochromeb sequences in the literature, including dolphin (Stenella) sequences, identified the cetaceans as monophyletic and the artiodactyls as their closest relatives. The comparison between the cytochromeb sequences of the fin whale andStenella showed that differences in codon positions one or two were frequently associated with a change in another codon position.

The complete nucleotide sequence of the mitochondrial DNA of the fin whale, Balaenoptera physalus.

The nucleotide sequence of the mitochondrial DNA (mtDNA) of the harbor seal, Phoca vitulina, was determined. The total length of the molecule was 16,826 bp. The organization of the coding regions of the molecule conforms with that of other mammals, but the control region is unusually long. A considerable portion of the control region is made up of short repeats with the motif GTACAC particularly frequent. The two rRNA genes and the 13 peptide-coding genes of the harbor seal, fin whale, cow, human, mouse, and rat were compared and the relationships between the different species assessed. At ordinal level the 12S rRNA gene and 7 out of the 13 peptide-coding genes yielded a congruent topological tree of the mtDNA relationship between the seal, cow, whale, human, and the rodents. In this tree the whale and the cow join first, and this clade is most closely related to the seal.

The complete mitochondrial DNA sequence of the harbor seal, Phoca vitulina.

Cyclopentadienyl metal complexes are organometallic compounds which exhibit antiproliferative properties in vivo and in vitro. They are represented by compounds of various structural type. The metallocene diacido complexes (C5H5)2MX2 contain early transition metal atoms such as titanium(IV) and vanadium(IV), the ionic metallicenium salts [(C5H5)2M]+X− include medium transition metals, e.g. iron(III), whereas the uncharged decasubstituted metallocenes (C5R5)2M comprise the main group elements tin(II) and germanium(II) as central metal atoms M. A variety of biological data are available about metallocene diacido complexes, especially titanocene dichloride. These substances exhibit antitumor properties against numerous experimental tumors, e.g. Ehrlich ascites tumor, B 16 melanoma, colon 38 carcinoma, Lewis lung carcinoma, as well as against various human tumors heterotransplanted to athymic mice. Biological experiments using (C5H5)2TiCl2 and (C5H5)2VCl2 pointed to the nucleic acids as a probable target for metallocene diacido complexes within the cells, revealed a main accumulation of titanium or vanadium in the liver and the intestine and unfolded a pattern of organ toxicity which fundamentally differs from that of other cytostatic drugs. These biological features confirm the cyclopentadienyl metal complexes to be an independent group of non-platinum-group metal antitumor agents being characterized by unusual biological properties. They represent interesting candidates for future biological and clinical investigations.

Transition and main-group metal cyclopentadienyl complexes: Preclinical studies on a series of antitumor agents of different structural type

Stereochemistry and lability of dihalobis(.beta.-diketonato)titanium(IV) complexes. II. Benzoylacetonates and dibenzoylmethanates

The rate constant of the thermal aquation of chromium complex (Cr(phen)/sub 3//sup 3 +/(phen = 1,10-phenanthroline)) has been determined as a function of pH and temperature; the quantum yield of the photoaquation has been evaluated as a function of excitation wavelength, as a function of pH in the presence of excited-state quenchers iodide, oxygen (I/sup -/, O/sub 2/), and as a function of substrate concentration. The luminescence lifetime and intensity from the /sup 2/T/sub 1///sup 2/E excited states have been measured as a function of pH, (O/sub 2/), (I/sup -/), and (Cr(phen)/sub 3//sup 3 +/). The absorption spectrum of the /sup 2/T/sub 1///sup 2/E excited states has been obtained; the decay of the absorption has been monitored as a function of temperature and solution medium. The thermal, photochemical, and photophysical behavior of Cr(phen)/sub 3//sup 3 +/ in aqueous solution is very similar to that exhibited by Cr(bpy)/sub 3//sup 3 +/ (bpy = 2,2'-bipyridine) and is interpreted in terms of analogous mechanistic steps. It is believed that excitation into spin-allowed states yields /sup 4/T/sub 2/, which undergoes very efficient intersystem crossing to /sup 2/T/sub 1///sup 2/E: these latter states can depopulate via nonradiative decay (including ground-state quenching) or interact with H/submore » 2/O and hydroxyl radicals (OH/sup -/) to yield a Cr(phen)/sub 3/(H/sub 2/O)/sup 3 +/ intermediate, which is the direct precursor of the aquation products. Back intersystem crossing is not regarded as an important process. The thermal aquation of the ground state is visualized as occurring via the same intermediate. The relationship of the results reported here to photoracemization and thermal racemization observatons in the literature is made. 11 figures.« less

Nick Serpone

Papers

Stereochemistry and lability of dihalobis(.beta.-diketonato)titanium(IV) complexes. II. Benzoylacetonates and dibenzoylmethanates

Photochemical, photophysical, and thermal behavior of the tris(1,10-phenanthroline)chromium(III) ion in aqueous solution

Determination ofNucleotide Sequences inDNA

Compounds Containing complex Boron Cations: Cationic Bis(2,4‐pentanedionato) boron(III) Complexes