Methylenecycloproparenes: efficient fluorescence and lasing of dimethylaminophenyl derivatives

Combining aromaticity and strain with Tetsuo Nozoe--a passage of time with friends

Note from the Editor: Tetsuo Nozoe lived his entire life on one of several island nations (Japan and Formosa, subsequently Taiwan, then returning to Japan). Those of us--and that is most of us!--who have never lived on an island nation likely cannot completely appreciate the 'isolation' and 'lack of diversity' that accompanies--along with many other valuable and happy consequences--such a life experience. As a New Zealander, colloquially as a Kiwi, Brian Halton shares this life experience with Nozoe. Indeed, New Zealand is far more isolated than either Japan or Taiwan in terms of distance to its nearest neighbor, population density, and size of its chemical community. Often during his career, Halton travelled to foreign lands, as did Nozoe, to fill his cup with collegiality and science. And Halton welcomed visitors to his beautiful country, as did Nozoe. Indeed, their mutual friendship was a blessing and honor to each of them. As Brian Halton tells his story of place and of science, I can well imagine Tetsuo Nozoe's response if he could read these words. He surely would have beamed in understanding these shared experiences!--Jeffrey I. Seeman Guest Editor University of Richmond Richmond, Virginia 23173, USA E-mail: jseeman@richmond.edu.

π-Extended Alkylidenecycloproparenes

Reaction of benzene-1,4-dicarboxaldehyde with anion 6 derived from 1,1-bis(trimethylsilyl)cyclopropa[b]naphthalene 1 gives 4-(methylidene-1H-cyclopropanaphthalenyl)benzaldehyde 7 as a minor product and 1,4-bis(methylidene-1H-cyclopropanaphthalenyl)benzene 8 as the major product of the reaction. With 4-{(E)-2-[4-(dimethylamino)phenyl]ethenyl}benzaldehyde 14, this same anion affords the stilbene-substituted π-extended (1-arylmethylidene)cyclopropanaphthalene 15 as a sparingly soluble orange-red powder.

Studies in the Cycloproparene Series. The Formation of Charge-Transfer Complexes from 1-Aryl- and 1-Diarylmethylidene-1H-cyclopropa[b]naphthalenes

The only charge-transfer (CT) complex formed from (p-dimethylaminophenyl)methylidene-1H-cyclopropa[b]naphthalene 7a is with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) 1 in acetonitrile. The methoxy-, thiomethyl-, and unsubstituted-phenyl analogues 7b–7d complex only with 2,3,5,6-tetrafluoro-7,7,8,8-tetracyano-1,4-benzoquinodimethane (TCNQF4) 2, and then only in dichloromethane; TCNQ 3, TCNE 4, and the o-CA 5 and p-CA 6 are without effect on any of 7a–7j. In contrast, the bis(dimethylaminophenyl)methylidene homologue 9a complexes with each of 1–5 but is the only diaryl derivative to do so. The polar parent, 1H-cyclopropa[b]naphthalene, does not form a CT complex with any of the acceptors employed.