Syntheses and Properties of Donor−Acceptor-Substituted Molecules with a Bicyclo[2.2.1]heptane, a Bicyclo[2.2.2]octane, and a Tricyclo[3.3.0.03,7]octane Spacer

Abstract

Keywords: Electron transfer / DonorϪacceptor systems / Through-bond interactions / PolycyclesStarting from bicyclo[2.2.1]heptane-2,5-dione, bicyclo[2.2.2]-octane-2,5-dione and tricyclo[3.3.0.0 3,7 ]octane-2,6-dione we were able to synthesize donor−acceptor-substituted derivatives by condensation reactions. The components for the condensations were propanedinitrile (21) for the acceptor part, and diethyl [(naphthalen-1-yl)methyl]phosphonate (12), diethyl [(anthracen-9-yl)methyl]phosphonate (13), and diethyl [(pyren-1-yl)methyl]phosphonate (14). To condense propanedinitrile we used the Knoevenagel condensation and for the phosphonates we used the Wittig−Horner−Emmons proced-

Cycloproparenes

“…Eckert-Maksic and co-workers have assessed by theory (HF/6-31G* and single point MP2(fc)/6-31G*//HF/6-31G* procedures) the possible Wheland intermediates in the reaction of 2 with H + and these concur with capture of the electrophile at C-3. The results are used to support Mills-Nixon bond localization (see section V) in the direction indicated in 2 , and they have been coupled with comparable studies on as yet unknown C-1 heteroatom analogues. ,

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“…The recently prepared derivatives 291 from stellanone and stellanedione (see entries 64 and 65, Table 1) also show good fluorescence properties, but unfortunately the molecules are photolabile. 203 The infrared spectra of the cycloproparenes are unexceptional but fully compatible with the symmetry of the molecules. A combination aromatic double bond stretch with a three-membered ring skeletal vibration is responsible for a characteristic absorption at ca.…”

“…The results are used to support Mills-Nixon 201 bond localization (see section V) in the direction indicated in 2, and they have been coupled with comparable studies on as yet unknown C-1 heteroatom analogues. 202,203 When sterically unencumbered, the cycloproparene three-membered ring is opened by simple acids 197 and with halogens 2,63 in what is now recognized as a highly efficient benzylating reaction. The reaction could proceed by either opening the three-membered ring σ bond directly, or via initial capture of the electrophile by the aromatic π framework at C-1a.…”

“…Emission spectra for a range of derivatives have been obtained, and the cycloproparene lumophore assessed. 4,164,191,203,346 Without doubt, the amino auxochrome is the most effective, be it as the dimethylaminophenyl 168e/f or pyrrolyl 290 derivative.…”

Effect of through bond coupling and conformation on the photophysical properties of σ-bridged systems comprising a vinylnaphthalene donor and a dicyanovinyl acceptor

“…A comparison of the fluorescence spectra of these D-B-A systems with those of the corresponding donor-bridge systems showed that the driving force for photoinduced charge separation is only large enough to result in quenching of the fluorescence from the locally excited state(s) in solvents of medium or high polarity with naphthalene or pyrene as donor. 22 Because of higher extinction coefficients at the preferred excitation wavelength (300 nm), we chose naphthalene as substituent to investigate the photophysical behavior of the model systems 4, 5 and 6 shown in Scheme 1 in detail.…”