Targeted synthesis of meso-aryl substituted aromatic trans-doubly N-confused dithia/diselena [18] porphyrins (1.1.1.1) with NIR absorption: spectroscopic and theoretical characterization

Abstract

High yield synthesis and spectroscopic isolation of two hitherto unknown highly stable single conformer of meso-aryl substituted dithia/diselena trans-doubly N-confused porphyrins with fully π-conjugated [18] annulene structures are reported. In...

Chemical transformation of doubly N-confused porphodimethenes to variants of (anti)aromatic doubly N-confused porphyrinoids and σ-aromatic doubly N-confused isophlorinoids

“…It is worth mentioning that increasing N-confusion with possible donor carbon atom(s) oriented preferentially toward the transition metal ion provides a new technique for stabilizing organometallic compounds, particularly those with unusual oxidation states or distinctive transition metal intermediates. 5,9 Additionally and most importantly, controlled modifications of the basic framework of N-confused porphyrinoids result in unique optical and electronic properties that have no direct parallel in the chemistry of normal porphyrins. 5 The facile conversion of porphodimethene 6 to 8 thus prompted us to unravel oxidative dehydrogenation of 6 by using appropriate oxidant(s) that could lead to variants of doubly N-confused porphyrinoid(s)/isophlorinoid(s) via unique π-reconstructions within the macrocyclic moiety.…”

“…7 Owing to the fact that introduction of confusion into tetrapyrrolic macrocycles causes a significant loss of thermodynamic stability, 8 only a handful of reports (Chart S1†) are available in the field of doubly N-confused tetrapyrrolic porphyrins. 9 Hence, what remains surprisingly elusive so far is the chemical transformation of N-confused porphodimethenes to the corresponding N-confused porphyrinoids, though a few reports of porphodimethene–porphyrin inter conversion are available. 10 The inter conversion of porphodimethene–porphyrin seems to be driven apparently by the aromatic nature of the porphyrin, which increases thermodynamic stability.…”

Tailor-made aromatic porphyrinoids with NIR absorption

“…Supported by the scientific interest to study whether and how employment of thiophene/selenophene rings in the development of novel trans doubly N-confused porphyrinoids would modify the conformation, electronic properties and the aromaticity of the new macrocycle, Rath et al witnessed that N-TIPS pyrrole P180 and thiophene/selenophene dicarbinol P99 are the two most promising and significant building blocks made for each other for constructing highly aromatic and NIR absorptive trans -doubly N-confused dithia/diselena porphyrins 181 (Scheme 43). 84 The electronic absorption spectrum of the free base form of dithia/diselena trans N 2 CP 181 (Fig. 37) comprises of a sharp Soret band at 484 nm and well-defined Q-type bands at 562 and 618 and a broad band at 807 nm tailing up to 1020 nm typical of aromatic porphyrinoids.…”

“…It is worth mentioning that a slight modification of the parent frameworks of such porphyrinoids can effectively modulate the macrocyclic core planarity, aromaticity, inner nitrogen site acidity, and intrinsic optical/electrochemical properties. 83,84 Apparently, such scientific curiosity led Rath et al to investigate whether and how swapping an N-confused N -methyl pyrrole ring ( P177a , Scheme 47) with an N-confused pyrrole ring ( P200 , Scheme 48) in the synthesis of novel ferrocenyl embedded N-confused porphyrinoids would affect conformation, efficient (lack) π-electron conjugation, electronic properties and the aromaticity/nonaromaticity/antiaromaticity of the new macrocycles.…”

Perimeter Coordinated Diastereomeric Rh(I) Complex of Helically Twisted Weakly Aromatic Hybrid Singly N-Confused β–β Fused Ferrocenoporphyrinoids

“…In our pursuit to foster global macrocyclic aromaticity (antiaromaticity) with NIR absorption in the smallest N-confused porphyrinoids, very recently we reported [16] planar-antiaromatic trans -doubly N-confused porphyrinoids with NIR absorption and NIR absorbing planar-aromatic [18] dithia and diselena trans doubly N-confused porphyrinoids . This antiaromaticity–aromaticity switching via reshuffling of core N(s) with S/Se, and/or number of built-in carbo- or heterocycles, provided us clues for further development of novel N-confused porphyrinoids with fine-tuned properties. Additionally and most importantly, the chemistry of nonplanar aromaticity is an ever growing research field owing to the fact that deviation from planarity strongly perturbs the properties of π-systems .…”