Assembly of positively charged porphyrins driven by metal ions: a novel polymeric arrangement of cationic metalloporphyrin.
Crystallization and crystal structure analysis of chlorohydrates of either tri- or tetracationic copper porphyrins, namely copper(5,10,15-tris(N-methyl-pyridinium-4-yl)-20-pyridine-porphyrinato) (1) and copper(5,10,15,20-tetrakis(N-methyl-pyridinium-4-yl)-porphyrinato), respectively, have been performed. Two crystalline forms, 2 and 3, of the latter have been obtained under different preparation conditions. A novel kind of slipped stack chains of these cationic porphyrins has been detected. The pronounced saddle conformation of the porphyrin reveals pi-like interactions between the peripheral pyrrole Cb-Cb- "double bond" and the metal center. DFT calculations on the isolated porphyrins clearly show the HOMO orbitals with the correct topology to yield a bonding interaction among the stacked porphyrin units. To our knowledge, a slipped stack chain of positively charged porphyrins has never been previously reported, if the arrangement of faced units of monocationic metalloporphyrins or phthalocyanins is excluded.
Geremia
Silvano
S
Centro di Eccellenza di Biocristallografia, Dipartimento di Scienze Chimiche, Università di Trieste, via L. Giorgieri 1, 34127 Trieste, Italy.
Di Costanzo
Luigi
L
Nardin
Giorgio
G
Randaccio
Lucio
L
Purrello
Roberto
R
Sciotto
Domenico
D
Lauceri
Rosaria
R
Pichierri
Fabio
F
D002412:Cations; D003300:Copper / Q000737:chemistry*; D018360:Crystallography, X-Ray; D008665:Metalloporphyrins / Q000138:chemical synthesis* / Q000737:chemistry*; D008958:Models, Molecular; D008968:Molecular Conformation; D015394:Molecular Structure; D013816:Thermodynamics
D002412:Cations; D008665:Metalloporphyrins; D003300:Copper