Cis-dicarbonyl binding at cobalt and iron porphyrins with saddle-shape conformation.
Diatomic molecules attached to complexed iron or cobalt centres are important in many biological processes. In natural systems, metallotetrapyrrole units carry respiratory gases or provide sensing and catalytic functions. Conceiving synthetic model systems strongly helps to determine the pertinent chemical foundations for such processes, with recent work highlighting the importance of the prosthetic groups' conformational flexibility as an intricate variable affecting their functional properties. Here, we present simple model systems to investigate, at the single molecule level, the interaction of carbon monoxide with saddle-shaped iron- and cobalt-porphyrin conformers, which have been stabilized as two-dimensional arrays on well-defined surfaces. Using scanning tunnelling microscopy we identified a novel bonding scheme expressed in tilted monocarbonyl and cis-dicarbonyl configurations at the functional metal-macrocycle unit. Modelling with density functional theory revealed that the weakly bonded diatomic carbonyl adduct can effectively bridge specific pyrrole groups with the metal atom as a result of the pronounced saddle-shape conformation of the porphyrin cage.
Physik Department E20, TU München, James-Franck Strasse, D-85748 Garching, Germany.
Knud
K
Seufert
Marie-Laure
ML
Bocquet
Willi
W
Auwärter
Alexander
A
Weber-Bargioni
Joachim
J
Reichert
Nicolás
N
Lorente
Johannes V
JV
Barth
D002248:Carbon Monoxide / Q000737:chemistry; D003035:Cobalt / Q000737:chemistry*; D007501:Iron / Q000737:chemistry*; D008958:Models, Molecular; D008968:Molecular Conformation; D015394:Molecular Structure; D011166:Porphyrins / Q000737:chemistry*
D011166:Porphyrins; D003035:Cobalt; D002248:Carbon Monoxide; D007501:Iron
Science. 1999 Nov 26;286(5445):1719-22
10576735
Acc Chem Res. 2003 Nov;36(11):825-31
14622029
Acc Chem Res. 2001 Feb;34(2):137-44
11263872
Phys Rev Lett. 2010 Jan 22;104(3):036102
20366661
Chem Commun (Camb). 2006 Jan 21;(3):243-56
16391725
Chem Rev. 2004 Feb;104(2):561-88
14871135
Chemphyschem. 2007 Aug 24;8(12):1782-6
17636464
Biophys J. 2007 Jun 1;92(11):3764-83
17350996
Acc Chem Res. 2005 Dec;38(12):943-54
16359166
Phys Rev Lett. 2008 Jan 25;100(3):036807
18233024
J Am Chem Soc. 2007 Oct 10;129(40):12110-1
17877358
Chemphyschem. 2007 Feb 2;8(2):250-4
17167810
Science. 1999 Apr 16;284(5413):473-6
10205052
Annu Rev Pharmacol Toxicol. 2006;46:411-49
16402911
Science. 1971 Dec 24;174(4016):1295-302
4332625
Chemphyschem. 2008 Jan 11;9(1):89-94
18080258
J Biol Inorg Chem. 1999 Feb;4(1):99-110
10499107
Phys Rev Lett. 2005 Oct 14;95(16):166601
16241825