Superbenzene–Porphyrin Conjugates

Abstract

A free-base porphyrin carrying two hexabenzocoronene (HBC) substituents in a trans arrangement and its zinc complex have been prepared. The compounds were characterized extensively and found to form tricationic dimers in the gas phase. X-ray crystallography confirms for the zinc complex a profound π-stacking of the HBC moieties. In contrast, the free-base porphyrin incarcerates n-heptane which essentially prevents π-stacking. Upon excitation of the HBC substituents, efficient energy transfer to the central porphyrin is observed.

Multiple‐Porphyrin Functionalized Hexabenzocoronenes

“…Steady-state fluorescences pectraw erem easured ( Figure S12, Supporting Information) and showedu pon excitation of the HBCs' b-banda ne fficient energy transfer to the porphyrins yielding only their fluorescencea t6 53 and 718 nm. [33][34][35]38] Generally,t he influence of substitutionp attern and number of porphyrins on the steady-state fluorescence characteristics were less pronouncedc ompared with the changes of the UV/Vis absorption properties. All spectroscopic data are summarized in Ta ble2.…”

“…[22] Subsequently,t he compound class of porphyrin-HPBs expanded to al ibrary of extraordinary light-harvesting arrays. [22][23][24][25][26][27][28][29][30][31] Their oxidized derivatives, porphyrin-HBCs, [32][33][34][35][36][37][38][39][40][41] however,d id not evolve parallel to the discoveries of novel porphyrin HPBs, althought heir preparation seems to be the logical continuation of the HPB architectures.T he first directly linked porphyrin-HBC was reported in 2013, it was synthesized in an intramolecular oxidative cyclodehydrogenation reaction of the respective porphyrin-HPB. [33] The transformation, commonly known as "Scholl reaction", turns af lexible, nonconjugated HPB moiety into ap lanarized, aromatic HBC unit, which significantly influences the porphyrins'c haracteristics.…”

“…For example, due to an electronic coupling between the two p-systems, ab roadening and bathochromic shift of the UV/Vis absorption bands of the porphyrin was observed. In the recenty ears, compounds,i nw hicho ne porphyrin is meso-connectedt os everal HBCs (up to four), [34,35,38] to graphene nanoribbons [36] or even fused to HBC units, [39] were developed. However, systems in which one HBC is connected to several porphyrins have remained unknownu ntil very recently.T his year,o ur group reported the synthesis of as eries of bis-porphyrin-HBC conjugates (Figure 1), which wasu tilizedt os tudy the effects of the HBCs' substitution geometry.…”

Polyaromatic Hydrocarbon (PAH) Porphodimethene Conjugates: Conformational Features and Acid‐Anion Binding Properties

“…al. [8] Generally porphodimethenes could be synthesized by hydrogenation of porphyrin, or oxidation of calix[4]pyrrole, [9] while we present a straightforward synthetic strategy where PAH have been incorporated in 10,20-porphodimethene by [2 + 2] condensation [10] reaction of 5,5'-tetraalkyl dipyrromethane (2) with respective polyaromatic aldehyde (1) (benzene, hexaphenylbenzene (HPB), naphthalene, anthracene, pyrene, HBC) under mild Lindsey conditions using catalytic amount of trifluoroacetic acid (TFA) and dichloromethane (DCM) as solvent. [11] The progress of reaction was monitored by thin layer chromatography followed by 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) induced oxidation to give an orange colored tetramer which on purification by silica gel column chromatography gave the corresponding 10,20-bis-PAH-porphodimethene (Scheme 1).…”

Inserting Porphyrin Quantum Dots in Bottom‐Up Synthesized Graphene Nanoribbons

“…While bottom-up synthesized GNRs have been touted for their intrinsic exotic electronic, [21][22][23][24][25][26][27][28][29][30][31] magnetic, [25,[29][30][31][32] and optical properties, [16,27,28,[33][34] examples for the deterministic assembly of functional bottom-up synthesized GNRs heterostructures have thus far been limited to uncontrolled copolymerization of molecular precursors on metal surfaces [6,13,18,20] or the study of smallmolecule model systems in solution. [35][36][37] We herein report the solution-based bottom-up synthesis and characterization of a GNR heterostructure comprised of two segments of solubilized cove GNRs (cGNRs) linked by a substituted tetraphenylporphyrin core (1, Scheme 1) acting as a highly tunable molecular quantum dot (QD). While our synthetic strategy can be extended to a variety of bifunctional linkers (see Supporting Information), we herein focus on the integration of a disubstituted tetraphenylporphyrin (H2(TPP)) and its metal complexes into a cGNR-H2(TPP)-cGNR heterostructure.…”