Formation of a Fluorous/Organic Biphasic Supramolecular Octopus Assembly for Enhanced Porphyrin Phosphorescence in Air

Abstract

The trinuclear triangle-shaped system [tris{3,5-bis(heptafluoropropyl)-1,2,4-triazolatosilver(I)}] (1)a nd the multi-armed square-shaped metalloporphyrin PtOEP or the free porphyrin base H 2 OEP serve as excellent octopus hosts (OEP = 2,3,7,8,12,13,17, Self-assembly of octopus arms around ag uest molecule is apowerful strategy to obtain architectures in which the steric and electronic properties of the shell control the guest environment.[1] Octopus molecules represent ac lass of molecular hosts composed of ar igid core with multiple surrounding flexible substituents.Avariety of octopus hosts have been explored since the pioneering work of Vçgtle and co-workers.[1] On the other hand, p-p and metal-p interactions between an octopus core and an aromatic guest may act as driving forces towards an ordered one-dimensional (1D) octopus-like supramolecular array.N umerous 1D p-stacked and/or metal-mediated supramolecular polymers have been reported in the last decade.[2] Theu se of fluorous octopus arms may induce novel functions akin to those enabled by fluorous metal-organic frameworks (FMOFs) [3,4] or nonporous analogues thereof that bear fluorous surfaces.[5] The monovalent Ag I ,A u I ,a nd Cu I salts of 1,2,4-triazolate (Tz) readily assemble into discrete trinuclear macrocycles, [M 3 (Tz) 3 ], [6] which can serve as the octopus core while the six 3,5-substituents serve as flexible octopus arms. [7, 8] -3,5-(n-C 3 F 7 ) 2 Tz) 3 ](1)can be constructed and has excellent inclusion and optoelectronic properties. [9] Herein, we show that fluorous octopus 1 can be combined with porphyrin octopi to form biphasic double-octopus assemblies with fluorous and non-fluorous arms on opposite sides;t he corresponding nanoscopic phases thus display interesting inclusion properties.T he metalloporphyrin PtOEP and the free porphyrin base H 2 OEP (OEP = 2, 3,7,8,12,13,17,18-octaethyl-21H,23H-porphine) were selected because of their wide-ranging applications. [10][11][12] DFT calculations showed that the molecular electrostatic potentials (MEPs) of H 2 OEP and PtOEP exhibit an electronrich (p-basic) region at the center of the squares whereas [Ag 3 (m 1,2 -3,5-(n-C 3 F 7 ) 2 Tz) 3 ](1)isvery electron-poor (strongly p-acidic) at the center of the nine-membered ring (Scheme 1b). Thee lectron-rich regions in H 2 OEP and PtOEP are susceptible to quadrupole-quadrupole interactions with the strongly electron-deficient region of 1.T he difference between the Q zz values of 1 (+ 20) and the porphyrin systems (À24 for H 2 OEP; À30 for PtOEP) accentuates strong attractive interactions,w hich assist p-p and/or metal-p forces in the formation of the stacked pairs [