Expandierte Carbaporphyrinoide

Abstract

In diesem Aufsatz sollen die Fortschritte auf dem Gebiet der synthetischen expandierten Carbaporphyrinoide dargelegt werden. Die Entwicklung auf diesem Gebiet wird anhand von expandierten Porphyrin‐verwandten Systemen aufgezeigt, die eine Vielfalt von Bausteinen enthalten, mit deren Hilfe ein oder mehrere Kohlenstoffatome in die Kavität eingeführt werden. Die Ausführungen beginnen mit den Platyrinen – den Makrocyclen, die als Stammmolekül nicht nur der expandierten Carbaporphyrinoide, sondern der Klasse der Carbaporphyrinoide im Allgemeinen gelten. Nach einigen historischen Betrachtungen wird eine Vielzahl von expandierten porphyrinartigen Makrocyclen, die N‐fehlgeordnete oder neo‐fehlgeordnete Pyrrol‐Strukturelemente und verschiedene carbocyclische Untereinheiten enthalten, vorgestellt. Ein besonderer Schwerpunkt wird dabei auf die Anwendungen von expandierten Carbaporphyrinoiden in verschiedenen Bereichen gelegt, z. B. in der Organometallchemie, bei Schaltersystemen oder der Aromatizität. Abschließend wird ein kovalenter Käfig auf der Basis von expandierten Carbaporphyrinoiden vorgestellt.

Dicarba[26]hexaporphyrinoids(1.1.1.1.1.1) with an Embedded Cyclopentene Moiety—Conformational Switching

“…Expanded porphyrinoids represent an attractive group of macrocycles in view of their conformational flexibility,e xtraordinary reactivity,m ultimetal coordinationc hemistry,f acile redoxi nterconversions and ability to accommodate versatile electronic states including Mçbius and Hückel aromatic and antiaromatic species. [1,2] Enlargement of the macrocyclic frame, as compared to the basic tetrapyrrolic porphyrin, enables an access to different conformations, whichc an be controlled by externalf actors such as solvents polarity,m etal ions coordination and modifications of the oxidation or protonation states. [3] In particular, the conformational dynamics of hexaphyrins(1.1.1.1.1.1) has been extensively explored.…”

“…[4,5] The impressive collectionofexpanded (hetero)porphyrinsremains in contrastwith rather modest number of expanded carbaporphyrinoids. [2,5] In fact, the history of expanded carbaporphyrinoidsd ates backt o1 978, when Berger and LeGoff reported on conjugatedt etraazaannulene molecule [1,3,1,3]platyrin 1 (Scheme 1). [6] Later on, the horizontally expandeda nalogue of 1,[ 1,5,1,5]platyrin 2 was synthesized.…”

“…[7] The list can be completed here by carbasapphyrin 3, [8] benzocarbaporphyrinoids represented by 4, [9,10] azuliporphyrinoids, [8,11] includinga zulisapphyrin 5 and molecular hybrids as 32-thiaphenanthrisapphyrin 6, [12] whichf use polycyclica romatic hydrocarbonsa nd polypyrrolic units. [2,[13][14][15][16] The introduction of original carbocyclic motifs-cyclopentene or cyclopentadiene into expanded porphyrinf rames seemstobean important step in efforts to create novel organometallic environmentsa iming to explore their unusualr eactivity. [2,17] Originally,i ncorporation of ac yclopentadiene ring into the regular b-alkylatedp orphyrinic frame wasa chieved.…”

“…[2,[13][14][15][16] The introduction of original carbocyclic motifs-cyclopentene or cyclopentadiene into expanded porphyrinf rames seemstobean important step in efforts to create novel organometallic environmentsa iming to explore their unusualr eactivity. [2,17] Originally,i ncorporation of ac yclopentadiene ring into the regular b-alkylatedp orphyrinic frame wasa chieved. [18][19][20] Eventually,t he syntheses of meso-substituted 21-carbaporphyrin [21,22] and 21-carba-23-thiaporphyrin, [17,23,24] and their complexes were reported.…”

“…The inversion of cyclopentenyl and cyclopentadienyl moieties is unprecedented in porphyrinoid chemistry but such rearrangements were reportedf or pyrrole, N-inverted pyrrole or telluropheneu nits. [2] Significantly,t he 31,34-dicarba [26]hexachlorinsc onformations have been controlled by protonation status, concentration and nature of acid used. The described conformation flexibility is evidently accompanied by profoundc hanges of the inner core donor sets which, eventually,p rovides the route to construct tunable macrocyclic environments suitable for organometallic exploration.…”