The novel cyclophanes 1 and 2 have now been synthesized.1 An interesting question is whether the bent pyrenes portion of the two molecules remains aromatic. The bending angles is 93.8° in 1 and 95.8° in 2. This distortion is readily apparent in Figure 1, which presents their B3LYP/6-311G(d,p) optimized geometries. NICS computations were used to assess the aromaticity of the pyrene portion. The central rings of pyrene have NICS(0) = -4.4 ppm. The corresponding values in 1 and 2 are -4.5 ppm. The apical rings of pyrene have NICS(0)= -11.9 ppm, while the value is -11.1 ppm in 1 and -11.0 ppm in 2. These calculations indicate that the molecule retains much of the aromaticity of the parent pyrene despite the significant out-of-plane distortions.

Figure 1. B3LYP/6-311G(d,p) optimized geometries of 1 and 2.1




(1) Zhang, B.; Manning, G. P.; Dobrowolski, M. A.; Cyranski, M. K.; Bodwell, G. J., "Nonplanar Aromatic Compounds. 9. Synthesis, Structure, and Aromaticity of 1:2,13:14-Dibenzo[2]paracyclo[2](2,7)-pyrenophane-1,13-diene," Org. Lett., 2008, 10, 273-276, DOI: 10.1021/ol702703b.


1: InChI=1/C34H20/c1-3-7-31-27-17-23-13-15-25-19-28(20-26-16-14-24(18-27)33(23)34(25)26)32-8-4-2-6-30(32)22-11-9-21(10-12-22)29(31)5-1/h1-20H/b29-21-,30-22-,31-27-,32-28-

2: InChI=1/C82H52/c1-9-25-53(26-10-1)71-73(55-29-13-3-14-30-55)77(59-37-21-7-22-38-59)81-67-49-63-45-47-65-51-68(52-66-48-46-64(50-67)69(63)70(65)66)82-78(60-39-23-8-24-40-60)74(56-31-15-4-16-32-56)72(54-27-11-2-12-28-54)76(58-35-19-6-20-36-58)80(82)62-43-41-61(42-44-62)79(81)75(71)57-33-17-5-18-34-57/h1-52H/b79-61-,80-62-,81-67-,82-68-