Judy I-Chia Wu

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Despite its highly nonplanar geometry, the tub-shaped D2d cyclooctatetraene (COT) minimum is far from being an unconjugated polyene model devoid of important π interactions. The warped skeleton of D2d COT results in the large stabilization (41.1 kcal/mol) revealed by its isodesmic bond separation energy (BSE). This originates largely from the "two-way"(More)
The most refined nucleus-independent chemical shift index (NICS(0)(πzz)) and the extra cyclic resonance energies (ECREs), based on the block localized wave function (BLW) method, show that the aromaticity of all azines is like that of benzene. The same is true for aza-naphthalenes relative to naphthalene. The lower relative energies of isomers with vicinal(More)
The synthesis and X-ray characterization of two new dialkynylated diazatetracenes and the corresponding N, N-dihydrodiazatetracenes are reported. The dialkynylated heteroacenes are packed in a brick-wall motif that enforces significant overlap of their pi-faces. Cyclic voltammetry indicates that the dehydrogenated forms are easily reduced to their radical(More)
Like the larger nonplanar Möbius rings, porphyrinoid aromaticity is not due primarily to the macrocyclic π conjugation of the corresponding annulene perimeters. The block-localized wave function (BLW)-derived aromatic stabilization energies (ASE) of several porphyrinoids reveal that, on a per atom basis, the appended 6π electron heterocycles of(More)
Despite having 4n pi electrons, dihydrodiazapentacenes are more viable than their 4n+2 pi azapentacene counterparts. Ab inito valence bond block-localized wave function (BLW) computations reveal that despite having 4n pi electrons, dihydrodiazapentacenes are stabilized and benefit substantially from four dihydropyrazine ethenamine (enamine) conjugations.(More)
The reactivity and regioselectivity of the electrophilic chlorination, nitration, and alkylation of benzene derivatives were rationalized by comparing literature data for the partial rate factors (ln f) for these S(E)Ar processes with theoretical reactivity parameters. The Electrophile Affinity (Ealpha), a new quantity, is introduced to characterize(More)
Aromaticity, a highly stabilizing feature of molecules with delocalized electrons in closed circuits, is generally restricted to 'Hückel' systems with 4n+2 mobile electrons. Although the Möbius concept extends the principle of aromaticity to 4n mobile electron species, the rare known examples have complex, twisted topologies whose extension is unlikely.(More)
Computed aromatic stabilization energies (ASEs) and dissected nucleus independent chemical shifts (NICSπzz) quantify the effect of hyperconjugation on the (anti)aromaticities of the planar conformations of three, five, seven, and nine membered (CnHn)CR2 (R = H, SiH3, F) rings. CH2 and especially C(SiH3)2 groups supply two "pseudo" π electrons(More)
The geometries of a series of [n](2,7)pyrenophanes (n = 6-12) were optimized at the B3LYP/6-311G** DFT level. The X-ray crystal structures determined for the [9](2,7)- and [10](2,7)pyrenophanes agreed excellently with the computed structures. The degree of nonplanarity of the pyrene moiety depends on the number of CH2 groups in the aliphatic bridge and, as(More)
Computed association energies and dissected nucleus-independent chemical shifts (NICS) document the mutual enhancement (or reduction) of intermolecular interactions and the aromaticity of H-bonded substrates. H-bonding interactions that increase cyclic 4n + 2 π-electron delocalization boost aromaticity. Conversely, such interactions are weakened when(More)