Construction of artificial metalloenzymes is one of the most important subjects in bioinorganic chemistry, because metalloenzymes catalyze chemical transformations with high selectivity and reactivity under mild conditions. [1][2][3][4] There are several reports on protein design: introduction of metal binding sites, [1,3,[5][6][7][8] design of substrate binding cavities, [9][10][11][12] chemical modification of prosthetic groups, [13][14][15][16] and covalent attachment of metal cofactors. [2,[17][18][19][20] In particular, the covalent modification of proteins is a powerful tool for the generation of new metalloenzymes, while the efficiency of the modification is very much dependent on the position and reactivity of the cysteinyl thiol functional group.[2] Herein, we describe a novel strategy for the preparation of artificial metalloenzymes by noncovalent insertion of metal-complex catalysts into protein cavities. The resulting semisynthetic metalloenzymes, apo-myoglobin (apo-Mb) reconstituted with Cr III Schiff base complexes, are able to catalyze enantioselective sulfoxidation.Manganese(iii) and chromium(iii) Schiff base complexes are known to be catalysts for various oxidations in organic solvents. [21,22] Jacobsen, [23] and Katsuki [24]

Buckminsterfullerene and its related fullerenes have generated a rapidly growing and active research area."] The former is one of the most impressive molecules because of its cagelike, truncated icosahedral structure. This molecule, a weak electronacceptor, forms clathrates in the solid state."] The selective formation of a clathrate from C,, and calix[8]arenes was excellently utilized for the separation of C,, and C,0.[31 Supramolecular complexes of C,, in solution are limited in the aqueous systhough extremely weak charge transfer (CT) complexes ['] are known in organic solvents. Quite recently weak inclusion complexes of C,, and calix[6]arenes have been reported.16] Because of the smooth and dense surface of C,,, it can be bound through an accumulation of weak van der Waals interactions, even in organic solvents, if a host with a suitably complementary shape is selected. In this paper we report the binding of calix-[5]arene['] receptors to C,, in organic solvents and the crystal structure of the inclusion complex.A color change (purple +pale yellow) was observed in the solution of C,, upon addition of the receptor (1). The intensity of the shoulder in the guest's absorption band in the 400-470 nm region increased (Figure 1) with the addition of the receptor (1).

No abstract

No abstract

No abstract