Nickel(II) Bisporphyrin‐Fused Pentacenes Exhibiting Abnormal High Stability

Abstract

As eries of largely p-extended multichromophoric molecules including cross-conjugated, half cross-conjugated, conjugation-interrupted and linearly conjugated systems were synthesized and characterized.T hese multichromophoric molecular systems revealed interesting structural-property relationships.B isporphyrin-fused pentacenes Pen-1 b and Pen-2 a showed rich redox chemistry with 7a nd 8o bservable redox states,r espectively.T he linearly-conjugated bisporphyrin-fused pentacenes (Pen-1 b and Pen-2 a)p ossess much narrower HOMO-LUMO gaps (1.65 and 1.42 eV redox, respectively) and higher HOMO energy levels than those of their pentacene analogues (2.23 and 2.01 eV redox, respectively), similar to those of muchl ess stable hexacenes and heptacenes.A ne stimated half-life of > 945 hw as obtained for bisporphyrin-fused pentacene Pen-2 a,w hich is much longer than that of its pentacene analogue (BPE-P,h alf-life, 33 h).

Unsymmetric Pentacene- and Pentacenequinone-Fused Porphyrins: Understanding the Effect of Cross- and Linear-Conjugation

“…In particular, the pentacene-fused nickel porphyrin dimer exhibited abnormally high stability, which was >60 times more stable than that of the corresponding pentacene. 43 The unusual properties of these pentacenequinone-and pentacene-fused porphyrin dimers prompted us to investigate the underlying factors governing the observed redox and optical behaviors. The first questions to be answered are the following: Will other pentacenequinone-and pentacene-fused porphyrins display similar properties?…”

Hysteretic Three-State Redox Interconversion among Zigzag Bisquinodimethanes with Non-fused Benzene Rings and Twisted Tetra-/Dications with [5]/[3]Acenes Exhibiting Near-Infrared Absorptions

“…; n indicates the number of annulated benzene rings). [ n ]­Acenes are highly attractive molecules because their HOMO/LUMO levels and small band gap can be easily modulated by π-extension and the introduction of various substituents or steric strain to the acene core. − Thus, their optical and electrochemical properties can be fine-tuned. As a result, [ n ]­acenes are widely used as functional organic materials such as semiconductors, − fluorescent probes, − and optoelectronic devices. − There are two main approaches to their synthesis (Scheme a): elimination of small molecule(s) such as carbon monoxide from precursors, − and nucleophilic addition to quinones followed by reductive aromatization. , However, several problems may arise regarding the solubility and stability of the reaction intermediate with an increase in n .…”

Nickel(II) Bisporphyrin‐Fused Pentacenes Exhibiting Abnormal High Stability

“…achieved, generating the partially interrupted cross-conjugated porphyrin dimer 5.Subsequent reductive aromatization of 4a and 4b with tin chloride proceeded efficiently to give bisporphyrin-fused pentacenes Pen-1 b and Pen-2 a,r espectively.Both Pen-1 b and Pen-2 a are stable enough to undergo silica column chromatography.T he structure of Pen-1 b and Pen-2 a were confirmed with 1 Ha nd 13 CNMR spectroscopy, mass spectrometry,and X-ray crystallography.…”

“…X-ray crystal structures of 3, 4b, Pen-2 a [13]. a) Topview and b) side view of 3.c )T op view and d) side view of 4b.e )T op view and f) side view of Pen-2a.All hydrogen atoms are omitted for clarity.…”