Scrutinizing the Chemical Nature and Photophysics of an Expanded Hemiporphyrazine: The Special Case of [30]Trithia-2,3,5,10,12,13,15,20,22,23,25,30-dodecaazahexaphyrin

Abstract

Thirty π-electron-expanded hemiporphyrazines 1a-c have been prepared by crossover condensation reaction of 2,5-diamino-1,3,4-thiadiazole and the corresponding phthalonitrile (3) or diiminoisoindoline (4) derivatives. The expanded azaporphyrin hexamers have been unequivocally characterized by means of spectroscopic, crystallographic, and electrochemical techniques. Weak intramolecular hydrogen bonding imposes a planar conformation to macrocycles. However, the overall electronic delocalization is low, and the nature of the resulting [30]heteroannulene is nonaromatic, as confirmed by NMR studies, XR diffraction analysis, and calculation of the NICS(0) value. Studies on a wide range of physicochemical features including ground, excited, reduced, and oxidized states provide evidence for the wide applicability of these 30 π-electron-expanded hemiporphyrazines in processes involving electron transfer. A key asset of our work is the systematic development of spectroscopic and kinetic markers for the formation and decay of all of the aforementioned species. Thirty π-electron-expanded hemiporphyrazines evolve as broadly absorbing light harvesters with excited state energies of around 2.3 eV that are susceptible to facile one-electron reduction and one-electron oxidation reactions.

Homotrinuclear Сomplexes of [30]Trithiadodecaazahexaphyrine with Transition Metals: Ni(II), Cu(II) and Mn(II)

“…Thus, we found out that compound H 3 Hhp can be obtained in 23 % yield in refluxing ethylene glycol in 26 h. [23] The product obtained was characterized by MALDI TOF, IR, UV-Vis spectroscopy, and elemental analysis, and its spectroscopic parameters agree well with those reported elsewhere. [21,23] However, efficient metallation of 1 could be only achieved in phenol as a solvent, employing acetates of copper(II), nickel(II) and manganese(II) in homogenous medium (Scheme 1), where reagents are present in sufficiently high concentrations. Following the same procedure, metal complexes 2-4 were prepared.…”

“…[7][8][9] Among expanded compounds, Mc's of ABABAB-type (hemihexaphyrazine, H 3 Hhp) containing six consecutively interlinked 1,3,4-thiadiazole (A) and isoindole (B) subunits bridged by nitrogen atoms [10,11] induce a particular interest. Indeed, various substituted macroheterocyclic compounds of this type were synthesized to date [12][13][14][15][16][17][18] and their structures were confirmed by gas electron diffraction (GED) [19,20] and single crystal X-ray diffraction [21] methods. It was established that compounds of this type have a nonaromatic macrocyclic backbone containing 30 carbon and nitrogen atoms which form an expanded coordination cavity compared to that of porphyrins and phthalocyanines.…”

Synthesis and Properties of AABAAB-Type Macroheterocyclic Compounds with Fragments of 1,2,4- and 1,3,4-Thiadiazole

“…These data agree well with the published data for the compounds of ABABAB-type, in which there is an inversion of the three thiadiazole rings with the sulfur atoms pointing outward from the inner cavity. [14] i: POCl 3, t = 60 °C, t = 20-25 min Macroheterocyclic Compounds with 1,2,4-and 1,3,4…”

“…[9,10] Their structures were confirmed by gas electron diffraction and X-ray crystallographic analysis. [11][12][13][14] The compounds exhibit an expanded cavity which is able to contain up to three transition metal atoms, [8,15,16] possess high thermal stability, [17] show interesting electrochemical and photophysical properties [14,18] and are of particular interest as objects of supramolecular chemistry.…”

Synthesis of Tri(4-tritylphenoxy)- and Hexa(4-methylphenoxy)-Substituted Hemihexaphyrazines

“…[19][20][21][22][23][24][25] If compared with various aza-analogues of porphyrinoids, macroheterocyclic compounds of ABABABtype are the most scrutinized now. Their macrocyclic core is formed by alternation of three 1,3,4-thiadiazole and three pyrrole subunits connected with each other via aza-bridges.…”