SHORT COMMUNICATION Mesoscopic Globular Self-assemblies of Platinum(II) Complexes Containing Porphyrins Mariangela Castriciano, [a] Andrea Romeo, [a] Raffaello Romeo, [a] and Luigi Monsu' Scolaro* [a,b] Keywords: Platinum / Porphyrins / Nanostructures / Aggregation / Scanning probe microscopy Slow evaporation of an acetone or chloroform solution of the novel tetranuclear platinum(II) complex [Pt(Lau 2 dim)Me] 4 - (TpyP)(CF 3 SO 3 ) 4 [Lau 2 dim = didodecyldiimine; TpyP = Introduction The formation of organized supramolecular structures of chromophores with well-defined shapes and sizes is a topic of relevant interest. [1] Their potential application in energy storage and conversion, supramolecular catalysis, optics and electronics can be easily recognized. In this respect, porphyrins and their metal derivatives are important com- pounds due to their favorable photophysical, electronic and catalytic properties. These features are strictly related to their aggregation state and strongly depend on the micros- tructural environment. [2] Specifically tailored porphyrins can be easily dissolved in micelles or liposomes [3] obtaining systems that assume the required stability, rigidity and ori- entation to perform specific functions, for example to mimic cytochrome P-450. [4] Amphiphilic porphyrins have been ex- ploited in the preparation of simple micelles, [5] fibers [6] and vesicles, [7] while ‘‘octopus’’ porphyrins have shown their tendency to self-assemble in vesicles [8] or fibers [9] able to bind oxygen in an aqueous medium. The formation of por- phyrin wheels or rings in the mesoscopic range has been achieved by simple solvent evaporation. [10] Metal complexes can be conveniently exploited to syn- thesize properly modified porphyrins [11] or linked porphyrin arrays using the self-assembly idea. [12] We have recently re- ported on the application of platinum(II) organometallic complexes to the synthesis of tetrasubstituted porphyrins that are soluble in micellar phases. [13] We knew from a de- [a] Dipartimento di Chimica Inorganica, Chimica Analitica e Chimica Fisica and ICTPN-CNR, Sezione di Messina - Universita ` di Messina, Salita Sperone, 31-Vill. S. Agata-98166 Messina, Italy Fax: (internat.) +39-090/393-756 E-mail: monsu@chem.unime.it [b] INFM, Unita ` di Messina Salita Sperone, 31-Vill. S. Agata-98166 Messina, Italy Supporting information for this article is available on the WWW under http://www.eurjic.com or from the author. Eur. J. Inorg. Chem. 2002, 531-534  WILEY-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002 1434-1948/02/0303-0531 $ 17.50+.50/0 531 5,10,15,20-tetrakis(4-pyridyl)-21H,23H-porphyrin] on a glass surface affords globular micrometric sized aggregates. tailed kinetic investigation on cationic complexes of the type [Pt(N-N)Me(Me 2 SO)] + (N-N = a series of diamines or diimines) [14] that the coordinated Me 2 SO becomes very labile when N-N is a diimine. Therefore, we used the com- plex [Pt(Cy 2 dim)Me(Me 2 SO)] + (Cy 2 dim = dicyclohexyldii- mine) as a monofunctional building block for introducing the platinum molecular fragment and for accessing a specif- ically tailored porphyrin. [13] This paper describes the formation of globular mesos- copic aggregates by simple evaporation of solutions con- taining a novel 5,10,15,20-tetrakis(4-pyridyl)-21H,23H-por- phyrin (TpyP) derivative functionalized with a platinum(II) complex bearing long alkyl chains. Results and Discussion The synthetic route to the porphyrin platinum(II) com- plex [Pt(Lau 2 dim)Me] 4 (TpyP)(CF 3 SO 3 ) 4 (1) (Lau 2 dim = didodecyldiimine) can be summarized as follows (Scheme 1): (i) the diimine ligand Lau 2 dim is readily pre- pared, according to a literature method, [15] by reacting do- decylamine and glyoxal in methanol; (ii) in analogy with a well-established procedure, [14] the diimine ligand is reacted with the complex trans-[Pt(Me 2 SO) 2 MeCl] in methanol, in the presence of a stoichiometric amount of AgCF 3 SO 3 ; sep- aration of solid AgCl and cautious evaporation of the ex- cess solvent affords the sulfoxide complex [Pt(Lau 2 dim)Me- (Me 2 SO)](CF 3 SO 3 ); (iii) this latter compound is reacted with a stoichiometric amount of the TpyP porphyrin in chloroform leading almost quantitatively to the tetranuclear complex 1. The gradual platination of the porphyrin can be monitored easily in situ by 1 H NMR spectroscopy, by ti- trating a solution of TpyP with the sulfoxide complex. The aromatic region of the spectrum shows a decrease of the signals for TpyP and a matching increase of the peaks due to intermediate mono-, di- and trisubstituted species, af-