Unique Interaction between Directly Linked Laminated π Planes in the Benzonorrole Dimer

A Parallel‐Displaced Directly Linked 21‐Carba‐23‐Thiaporphyrin Dimer Incorporating a Dihydrofulvalene Motif

“…[11] Such ap rofound structural change was firmly confirmed by the position of C(21) resonances of 4 and 5 determined by 1 H-13 CH SQC experiment (113.6 ppm and 39.9 ppm, respectively). [6,13] TheN ICS value of each subunit, determined for the central 16-membered ring, equals À14.2 ppm evidently consistent with their diatropicity.T he alternative rotamer 5 ff with the face-to-face arrangement (the H(21)-C(21)-C(21)'-H(21')d ihedral angle: 4 7 8 8)i se vidently less stable as the energy difference between 5 pd and 5 ff equals 9.4 kcal mol À1 .In fact the structural model of 5 pd ,r eflects the structural constraints determined by NOE measurements (contact between H(2,3) and o-Me protons). Thel imited libration about single bond C(21)À C(21')ispossible but nevertheless restricted.…”

“…Presumably the process proceeds with ap rearrangement of 4 to acquire ag eometry of less stable tautomer resulting in the sp 2 to sp 3 rehybridization of the internal carbon atom. TheH (21)-C(21)-C(21')-H(21')d ihedral angle equals 1808 8.T he interporphyrin distance between two macrocyclic planes (defined by four meso carbons) equals 3.22 a nd is slightly larger to that observed for the reduced benzonorrole dimer with single bond (3.14 ), [6] however shorter than for 3 and other arrays with the face-to-face arrangement (over 3.4 ). [11] Thet wo DFT optimized rotamers of 5 are presented in Figure 3.…”

“…[4,5] Thef ace-toface dimer of benzonorrole with ad irect double bond between the internal carbon atoms (3)d emonstrating strong p-p interaction between two p planes was reported. [6] Originally the inclusion of b-substituted cyclopentadiene moiety into ap orphyrin frame yielding an aromatic carbaporphyrin with b-substitution at pyrrole rings was achieved by Berlin. [7] Lately Lash and co-workers described the synthesis of b-substituted carbaporphyrin via oxidation of carbachlorin with stoichiometric amount of DDQ.…”

“…[3][4][5][6] Thus the reaction of 5 with HX (X = Cl or Br,7-10 equiv) was followed by 1 HNMR spectroscopy (Scheme 3). Furthermore the dimer 5 is very sensitive for the presence of even trace amount of acid in solution and easily undergoes splitting to monomeric species.Such atransformation does not have any precedence in chemistry of covalently linked dimers of porphyrinoids.…”

Switch‐ON Near IR Fluorescent Dye Upon Protonation: Helically Twisted Bis(Boron Difluoride) Complex of π‐Extended Corrorin

“…Likewise, the direct linkage between the pyrrolic nitrogen and the α‐CH of neighbouring pyrrole gave the neo‐confused isomer ( 3 ) . These mutation strategies indeed lead to an emergence of distinct properties such as peripheral anion binding capability at the NH site and the formation of redox‐active laminated dimer through inner carbon‐carbon bonding . In this way, multiple utilization of an N‐confusion modification of the corrole yielded a doubly N‐confused isomer, namely corrorin ( 4 ) bearing a twisted bipyrrole moiety connected between β‐pyrrole and meso ‐carbon atoms .…”