Transanular Interaction in [2.2]Phanes: [2.2](2,7)Pyrenophane

Abstract

The eDlission spectra of [2.21 (2,7)pyrenophane and the zero field splitting parameters D und E of its excited triplet elate were measured in glasses and in amaU siogle cry .. ~.Ls at 1.3 .K. The .results are beiDg compand with monomer pyrene and 2.7·dimelbylpyrene in liqUid and solid solultons as weD as in lingle C1')'I1815.

[3.3]‐ and [4.4](2,7)Pyrenophanes as Excimer Models: Synthesis, Molecular Structure, and Spectroscopic Properties

“…This indicates that in the excited triplet state transanular interactions between the pyrene 1t-systems must be small. Accordingly, triplet zero field splitting parameters D and E. measured by the ODMR technique 4 ). are very similar for pyrenophanes and for pyrene monomers [1 : I D I '" 0.0842 cm -I. I E I = 0.0165 cm -I; 2.7-dimethylpyrene: I D I = 0.0855 cm -I. I E I '" 0.0169 cm -I ; in 2-methyltetrahydrofuran.…”

“…for generous support of this work. 4,5,9,: 10.0 g (25.5 mmol) of 2,7-bis(bromomethyl)-4,5,9,IO-tetrahydropyrene (3), prepared according to lit. 3>.…”

“…189-191 °C (lil,3» 190-192°C). 4,5,9,: To a suspension of 10.0 g (204 mmol) of sodium cyanide in 300 ml of dimethyl sulfoxide at 20 0 e 18.8 g (47.7 mmel) of 3 was added under stirring. After 30 min the reaction mixture was added to 1.5 I of ice water, the precipitate was filtered off, washed with water, dried, and chromatographed from dichloromethane on silica: 11.3 g (83%); after recrystallisation from isopropyl alcohol/toluene (4: I) and sublimation al 16O-170 o eIl0 -3 Torr m.p.…”

“…Recently, compounds with two aromatic units fixed intramolecularly in a well-defined geometry found increasing interest as excimer models 2 ). In this connection [2.2) (2,7)pyrenophane has been synthesized 3) which in fact shows spectroscopic properties in accordance with an intramolecular excimer analogue 4 ). As X-ray structure analysis showed, however, the aromatic rr-systems in [2.2](2,7)pyrenophane deviate strongly from planarity due to the high sterical strain present in this [2.2]phane structure 3d).…”

“…Dehydrogenation (Pd/C, I-methylnaphthalene, 24 h, 245°C) converted 11 into 1 (72% Synthesis of [4.4](2, 7)Pyrenophane (2) As in the case of the synthesis of I, the preparation of the higher homologue 2 started from 2,7-bis(bromomethyl) -4,5,9,10-tetrahydropyrene (3) which by malonic ester synthesis yielded 2,7 -bis [2,2-bis(methoxycarbonyl)ethyl)-4,5, 9,1 O-tetrahydropyrene (12, 90%). By demethoxycarbonylation 6 ) (NaCIIH 2 0, dimethyl sulfoxide, 3 h, 160 -170°C; 59%), 4,5,9, 1O-tetrahydro-2, 7-bis[2-(methoxycarbonyl)ethyl)pyrene (13) was obtained which via 4,5,9,pyrene (14; by lithium aluminum hydride reduction of 13; 97%) was converted into the bis(bromopropyl) compound IS (tetrabromomethane, triphenylphosphane; 73%). Cyc1isation of 15 with the bis(mercaptomethyl) compound 4 (potassium carbonate, methanol, high dilution) yielded 8,9,13,14,23,24,28,29-octahydro-2,19-dithia[5 .5) (2,7)-pyrenophane (16; 291170) which was oxidized to the corresponding disulfone 17 (3-chloroperoxybenzoic acid, chloroform; 861170).…”