᎐
R = C᎐CSiMe3: 382 (3.86), 438 (5.33), 476 (3.41), 526 (3.36), 563 (3.70),
8 with zinc() porphyrin-2,3-dione 2 and NH4OAc in AcOH–
CHCl3 at reflux for 72 h. This reaction gave the novel dizinc()
bisporphyrin 20† in 42% yield (Scheme 4). The zinc-to-zinc
distance in arene-linked bisporphyrin 20 was calculated12 to be
18.5 Å which is significantly shorter relative to the zinc-to-zinc
distance in the dizinc() bis(imidazoporphyrin) 16 (ca. 28.3 Å)
and between the zinc ions in the terminal porphyrins of the
trizinc() tris(imidazoporphyrin) 19 (56.6 Å).
᎐
597 (3.99), 653 (3.40), 692 (3.20); 12: 326 (4.65), 420 (5.48), 517 (4.45),
552 (4.15), 587 (4.09), 640 (3.69); 15: 310 (4.41), 427 (5.43), 480 (3.39),
492 (4.31), 514 (3.68), 586 (4.03); 16: 348 (4.74), 426 (5.70), 513 (4.16),
550 (4.71), 587 (4.45); 17: 242 (4.66), 427 (5.85), 519 (4.75), 556 (4.38),
589 (4.29), 649 (3.91); 18: 241 (4.60), 429 (5.39), 519 (4.50), 552 (4.56),
588 (4.36), 649 (3.56); 19: 250 (4.82), 352 (5.01), 369 (5.00), 429 (5.87),
454 (5.83), 519 (4.50), 554 (4.87), 596 (4.80); 20: (toluene) 321 (4.60),
431 (5.68), 458 (5.43), 516 (4.15), 554 (4.69), 589 (4.42).
The use of these novel compounds and systems to probe
further the influence of porphyrin orientation and alignment
on interporphyrin electronic communication is under active
investigation in our laboratory.
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Acknowledgements
We thank the Australian Research Council for a research grant
to M. J. C.
Notes and references
† All imidazoporphyrins have been fully characterised by elemental
analysis, mass spectroscopy, 1H NMR spectrometry and spectro-
scopic techniques. Visible spectroscopic data of selected porphyrins:
5,10,15,20-tetrakis(3,5-di-tert-butylphenyl)porphyrin: λmax(CHCl3)/nm
405sh (log ε 4.91), 422 (5.66), 487sh (3.66), 519 (4.28), 555 (4.04), 593
(3.78), 648 (3.85); 3: 317 (4.30), 424 (5.50), 484 (3.75), 519 (4.23), 554
(4.02), 587 (3.89), 646 (3.45); 4: 422 (5.51), 519 (4.24), 554 (4.00), 588
(3.94), 647 (3.85); 6: 423 (5.51), 519 (4.35), 554 (4.01), 588 (3.92), 649
(3.62); 8: 346 (4.42), 431 (5.42), 524 (3.90), 550 (4.29), 592 (4.05); 9
11 T. Förster, Faraday Discuss. Chem. Soc., 1959, 27, 7.
12 SPARTAN version 4.0, Wavefunction Inc., Irvine, CA, USA, 1995.
Communication 9/05507J
J. Chem. Soc., Perkin Trans. 1, 1999, 2429–2431
2431