340
E.B.A. Filho et al. / Chemical Physics Letters 449 (2007) 336–340
effects. However, it is observed that the values of $2q(r)
presented here are much smaller than the ones obtained
at BCP for common covalent interactions. The AIM calcu-
lations on 4b characterize an IHB involving a seven mem-
ber ring [24–26], such as the OHꢀ ꢀ ꢀO N@O.
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IR and 1H NMR data have also supported the existence
of a seven member ring IHB in 4. The IR spectroscopic
data shows the existence of a broad band corresponding
to the O–H stretching (m = 3472–3420 cmꢁ1) in 4, differing
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1
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1
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In this Letter a new procedure to prepare a new class of
bioactive compounds 3 and 4 is presented, along with a
corresponding computational and spectroscopic study in
gas phase and water media. The efficiency of a RPESS
methodology for a rational search of conformers for the
aforementioned adducts is also demonstrated, since the
most stable anti-periplanar 2d and 3d conformations in
gas phase were only found using this protocol. The PCM
model demonstrated to be important for the relative stabil-
ities of the conformations 1d and 2d. AIM calculations and
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´
´
´
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˜
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1
spectroscopic (IR, H NMR) data have shown to be com-
plementary in order to characterize intramolecular hydro-
gen bonds (IHB) in 1 and 4.
Acknowledgments
FAPESQ, CNPq and Profa. Regiane C.M.U. Arau´jo
for providing computational facilities.