Shojiro Ogawa

Preparation of a conjugated tautomer of 1,14:7,8-diethenotetrapyrido-[2,1,6-de:2′,1′,6′-gh:2″,1″,6″-kl:2‴,1‴,6‴na][1,3,5,8,10,12]hexa-azacyclotetradecine and its metal derivatives

A hexa-aza-macrocyclic compound of high thermal stability is readily obtained from 2,9-diamino-1,10-phenanthroline by its thermolysis or by its condensation with 2,9-dihalogeno-1,10-phenanthroline. The structure of this macrocycle has been established as a conjugated system of a novel type, related to some extent to porphin and phthalocyanin. The macrocyclic compound forms copper, cobalt, and nickel complexes.

A tautomerisable macrocyclic compound containing two aza-bridged 2,2′-bipyridine moieties

A novel macrocyclic compound containing two aza-bridged 2,2′-bipyridine moieties was prepared by the templated reaction of 6,6′-dichloro-2,2′-bipyridine. Spectroscopic investigation shows that the aza-bridging atoms form an amine ⇌; imine tautomeric system. The tautomerism is dependent upon the solvent; the imine form is preferred in non-polar solvents such as chloroform and benzene, while the amine form is favoured almost exclusively in polar solvents such as water, alcohol, acetonitrile, dimethyl sulphoxide, or tetrahydrofuran.

Lithium complexation of configurational isomers of tetra-aza macrocycle containing 2,2′-bipyridine. X-Ray molecular structure of the trans-isomer of a dibutyl dicyano macrocycle

Two configurational isomers of a dicyano dibutyl tetra-azamacrocycle containing four pyridine rings were obtained. The cis-isomer showed a higher complexing ability toward Li+ and Li+/Na+ selectivity than did the trans-isomer. The trans-isomer, the structure of which was established by X-ray analysis, displayed marked spectral changes due to significant conformational changes upon complexation.

Preparation of macrocyclic compounds by thermal dimerization of 1,10-phenanthroline derivatives

An efficient non-template synthesis of a new macrocycle, a conjugated tautomer of 1,14 : 7,8-diethenotetrapyrido-[2,1,6-cd:2′,1′,6′-gh :2″,1″,6″-jk:2‴,1‴,6‴-na][1,4,8,11]tetra-azacyclotetradecine (3), is described. The thermal behaviour of several disubstituted 1,10-phenanthrolines towards dimerization is studied by use of differential thermal analysis and thermogravimetric analysis, and some spectroscopic properties of the macrocycles produced are described.

Non-template syntheses and monoalkylation of an aza macrocycle containing 2,2′-bipyridine

Cross-condensation of 6,6′-diamino-2,2′-bipyridine (3) with 6,6′-dibromo-2,2′-bipyridine (2) gave an azamacrocycle containing two aza-bridged 2,2′-bipyridine moieties, 3H,10H-tetrapyrido[2,1,6-de:2′,1′,6′-gh:2″,1″,6″-kl:2‴,1‴,6‴-na][1,3,5,8,10,12]hexa-azacyclotetradecine (1), in high yield without metal template. Furthermore, compound (1) could be obtained in >90% yield directly from 6,6′-dibromo-2,2′-bipyridine (2) by heating the latter with ammonia in an autoclave without metal template. N-Alkylation of compound (1) with n-hexyl bromide in the presence of tetra-n-butylammonium bromide gave exclusively the mono-N-n-hexyl derivative of (1), 10-hexyl-3H,10H-tetrapyrido[2,1,6-de:2′,1′,6′-gh:2″,1″,6″-kl:2‴,1‴,6‴-na][1,3,5,8,10,12]hexa-azacyclotetradecine (4). Evidence for the tautomerism of the mono-n-hexyl derivative (4) was provided by the 1H n.m.r. and absorption spectra.

A molecular orbital study on a tetra-aza macrocycle containing 2,2′-bipyridines and its lithium complex

Singlet transition energies and oscillator strengths of two configurational isomers of a dicyano dibutyl tetra-aza macrocycle containing four pyridine rings and their lithium complexes were calculated using the CNDO/S CI method at ab initio RHF/3-21G optimized geometries. The results were in good agreement with those derived from the UV-Visible absorption spectra. The drastic spectral changes observed upon complexation in the trans-isomer were found to be due to the significant conformational change in the bipyridine moiety and the resulting energy separation of the frontier π orbitals. The close proximity between the triplet states and the singlet excited state suggested that the intersystem crossing might occur in the trans form of the lithium free macrocycle. This is one of the possible explanations of the large discrepancy in fluorescence intensities between the trans-isomer of the macrocycle and its lithium complex.

Synthesis of a novel macrocyclic compound and of its copper complex

Condensation of 2,9-diamino- and 2,9-dichloro-1,10-phenanthroline gave a novel macrocyclic ligand in excellent yield.

The Efficient Separation of Lithium Chloride by Acyclic Carrier Molecules

A new acyclic carrier molecule (1) (2,9-didodecanoylamino-1,10-phenanthroline) for the separating purpose of lithium chloride was synthesized by a simple, short synthetic route. Carrier (1) exhibited the high selectivity for binding to the Li + ion, and has enough ability to form a stable complex consisting of one carrier (1) and one Li + ion. LiCl is separated efficiently from the mixture of various alkali metal chlorides by using liquid membranes containing carrier (1). The transport rate and selectivity by carrier (1) can are changed by the concentration of metal salts and the properties of anion in the source phase. Two different transport mechanisms are proposed for the explanation of this transport result and molecular orbital calculations on two proposed carrier (1)-Li + complexes provide a possibility of supporting above explanation. The numerical simulation of Li + transport using the rate equation of a simple model suggests that the transport by carrier (1) is promoted due to the diffusion limited process and this property is similar to other previously reported macrocyclic carrier molecules. These results indicate an important fact that simple, acyclic compounds have enough ability as LiCl carrier, though the complicated macrocycles with small cavity have been known as Li + ion selective carriers.

UNUSUAL REACTIONS OF THE HIGHLY STRAINED MACROCYCLES WITH LITHIUM SALTS: ANION CONTROL FOR THE REACTION RATES AND ELUCIDATION OF THE PROPERTIES OF THEIR LITHIUM COMPLEXES

The complexation reactions of dicyano monoalkyl tetraaza macrocycle 3b with lithium salts (Li + X - ) and the properties of resulting macrocycle 3b-Li + X - complexes were examined in detail by means of 1 H-NMR spectroscopy, because unsymmetrical macrocycle 3b has exhibited intriguing features, such as high selectivity for binding to the Li + ion. The following noticeable facts were found; the reaction rates of complexation are heavily controlled by the properties of anion (X - ) and the spectroscopic properties of macrocycle 3b-Li + X - complexes are also changed by the anion. The major origin for the unusual Li + complexation reactions and the specific behavior of Li + complexes would come from the unique properties of metal free macrocycle 3b, because macrocycle 3b has a strong intramolecular hydrogen bond in the macrocyclic ring and the highly strained macrocyclic ring by unsymmetrical structure consisting of nonplanar and planar moieties.