Design and Synthesis of Porphyrins Bearing Rigid Hydrogen Bonding Motifs:  Highly Versatile Building Blocks for Self-Assembly of Polymers and Discrete Arrays

Abstract

Two aldehydes, 2,6-diacetamido-4-formylpyridine (7) and 1-butyl-6-formyluracil (11), are used to synthesize five pyridyl and four uracyl meso-subsituted porphyrins. With these complementary porphyrin building blocks, it is possible to build various types of multi-porphyrin supramolecules with different spatial relationships in predefined geometries. The formation and properties of self-complementary dimers and a closed tetrameric square are presented as a basis of comparison to the latter system in the solid state. An X-ray structure of 5,10-bis(4-tert-butylphenyl)-15,20-bis(3,5-diacetamido-4-pyridyl)porphyrin confirms its molecular structure and reveals a hydrogen-bonded supramolecular organization mediated by water molecules.

Tuning the hydrogen-bonding strength in 2,6-bis(cycloalkylcarbonylamino)pyridine assemblies by variable flexibility. Association constants measured by hydrogen-bonded vs. non-hydrogen-bonded protons

“…Triple hydrogen-bonded associates are met in many structures as in DNA [14,15], amides [16,17], artificial sensors [18][19][20][21][22], materials [23], non-covalent polymers [4,[24][25][26][27][28] and in recently observed associates of orotic acid [29,30]. Triple hydrogen-bonded assemblies carrying 2,6-diaminopyridine DAD-hydrogen bonding moiety were studied by some groups with the use of various methods [4,6,[31][32][33][34][35][36][37][38][39][40][41][42][43][44][45][46][47] and also by us [48,49]. We noticed that the use of NH and CH proton shifts as probes in Previously [48] we confirmed results from other group [50] reporting that the 2,6-bis(acylamino)pyridine do not dimerize.…”

Self-organization of self-assembled photonic materials into functional devices: Photo-switched conductors

“…In the present case, diacetamidopyridyl groups are complementary to uracil groups (Fig. 1, assembly 3) (19). A second H-bondassembled array is formed from dibutlybarbituric acid and triaminotriazine appended with two zinc tetraphenylporphyrin (ZnTPP) moieties.…”

“…In principle, as observed for other systems, the use of the much more labile Mg(II) porphyrins should increase the electron transfer efficiency by increasing the singlet excited-state lifetime (27). It is well understood that the length of linear self-assembled systems is dictated by the thermodynamics of the intermolecular interactions (2,7,8,19), but in this case the length is also governed by the width of the bilayer, vide infra. The combination of a set of two porphyrins in a 2:2 ratio (one bearing two pyridyl groups at 180°and one bearing a single pyridyl group) with three trans palladium units forms a population of linear systems with substantial rotational and conformational flexibility (Fig.…”

“…The entire system is enclosed in a copper Faraday cage resting on a vibration-damping table (both homemade). The porphyrin synthesis and characterization of both linear and square arrays are also described elsewhere (18)(19)(20)(21).…”

“…In general, the self-assembly of discrete porphyrin arrays can be accomplished by hydrogen bonding (18,19,25,26) or metal ion coordination (20,21,25,26) in organic solvents. Three linear tapes and one system (18) that may be linear, irregular, or circular are used in the photogated conducting devices described below.…”