Excimer Fluorescence from anti-[2.3](2,7)Phenanthrenophane

Abstract

In the [2.3](2,7)phenanthrenophanes prepared by the intramolecular [2 + 2] photocycloaddition of 1,3-bis(7-vinyl-2-phenanthryl)propane, excimer fluorescence was observed for not only syn- but also anti-isomer, though the maximal position of the latter was slightly blue-shifted relative to the former.

Synthesis and Fluorescence Spectra of Oxa[3.n]phenanthrenophanes

“…The aromatic protons of syn-6b and syn-7 are almost equally high-field shifted compared to those of precursors such as 8b and 9, as observed in the syn-phenanthrenophanes reported previously. [7][8][9][10] This observation demonstrates that the two phenanthrene nuclei are wholly overlapped with each other.…”

“…Noticeably, syn - 1 , whose phenanthrene rings are held almost in parallel, enabled the first observation of excimer fluorescence almost free from monomer fluorescence at room temperature . The first preparation and isolation of various anti -phenanthrenophanes with partially overlapped phenanthrene rings, such as 3 , 4 , and 5 , were also accomplished by the intramolecular [2 + 2] photocycloaddition of vinylphenanthrene derivatives, although Staab et al had obtained a mixture of syn - and anti -[2.2](2,7)phenanthrenophane. ,

1 Phenanthrenophanes so far prepared.

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“…The excimer fluorescence of syn-7 is the most red-shifted (λ max ) 432 nm) among the excimers of phenanthrenophanes so far observed. [7][8][9][10] This large peak shift in syn-7 is ascribed to its arrangement where the distance between the two fully overlapped phenanthrene nuclei is moderately short due to the bridging by two trimethylene-type linkages leading to larger stabilization energy in the excited state and larger repulsion energy in the ground state. The trimethylene-type linkages appear to be more suitable for excimer formation than the others, such as a cyclobutane, in agreement with Hirayama's rule.…”

Photochemistry of Cyclobutanes: Synthesis and Reactivity

“…This treatment gives a 40% yield of a mixture of the two phenanthrenophanes syn-156 and anti-157 in a ratio of 1:1.3. No interconversion of these compounds takes place at ambient temperatures 109 . Linking via the 9 positions of the phenanthrene moieties and the vinyl groups on C3 occurs on irradiation of the phenanthrene derivative 158.…”

Stereocontrol in Cyclophane Synthesis: A Photochemical Method To Overlap Aromatic Rings

“…It is noteworthy that various regioisomers are possible for mono- and divinylphenanthrenes due to the low symmetry of the phenanthrene nucleus. Among them, the vinylphenanthrenes and their derivatives shown in Tables and successfully gave the corresponding phenanthrenophanes by the inter- 25 or intramolecular − photocycloaddition. Both 1,6- ( 64 ) and 3,6-divinylphenanthrenes ( 65 ) efficiently afforded syn -[2.2]phenanthrenophanes 66 and 67 and 68 − 70 , respectively, whereas 2,7-divinylphenanthrene failed to give the corresponding phenanthrenophane, probably for steric reasons, similar to the case of p -divinylbenzene and 1,4-divinylnaphthalene.…”