Ureidobenzotriazine Multiple H-Bonding Arrays:  The Importance of Geometrical Details on the Stability of H-Bonds

Abstract

A 3-ureidobenzo-1,2,4-triazine 1-N-oxide (1) was synthesized successfully. The derivative displays an acceptor-donor-acceptor-acceptor (ADAA) hydrogen-bonding motif in CDCl 3 and DMSO-d 6 solution as well as in the solid state. Although moderately strong association of 1 was observed with DAD motifs, nonspecific binding is observed with ureidopyridines featuring a complementary DADD array. Density functional calculations of conformations 1a and 1b together with two complexes revealed the clearly nonplanar geometry of the multiply hydrogen-bonded complex, in which some bonds are significantly longer (3.2 Å) than is optimal for H-bonds. As a result, only very small free energies of association were calculated, in line with the experimentally observed absence of specific assembly of the components.

Complexation of Phenol and Thiophenol by Amine N‐Oxides: Isothermal Titration Calorimetry and ab Initio Calculations

“…[57] The geometries of the monomers and complexes were optimized at the B3LYP/6-311G(d,p) and M062X/6-311G(d,p) levels of theory, which generally describe the geometries of these systems well. [18,20,37,38,58] All B3LYP/6-311G(d,p)-optimized stationary points were confirmed as true minima through vibrational frequency calculations. The B3LYP/6-311 + G(d,p) method and the MP2 and SCS-MP2 methods both with the small [6-311 + G(d,p)] basis set were chosen to ensure that the conclusions are not influenced by significant method-dependent phenomena.…”

“…Recent computational studies show that accurate geometric information is required to make meaningful predictions. [20] Herein, the interaction between the phenols and the extractants is experimentally investigated in detail by isothermal titration calorimetry (ITC) binding experiments. Although some information about hydrogen bonding of phenols to amine Noxides is already available, [6,[13][14][15] it was obtained indirectly from IR measurements and from liquid-liquid extraction experiments.…”

Hydrogen Bonding in Phosphine Oxide/Phosphate–Phenol Complexes

“…Herein, the geometries of the monomers and complexes were all optimized at the B3LYP/6-311G(d,p) level of theory, which generally describes the geometries of these systems well. [50,51] All B3LYP/6-311G(d,p)-optimized stationary points were confirmed as true minima via vibrational frequency calculations. If not indicated otherwise, the 6-311 + G(d,p) basis set was used for energy calculations.…”

The synthesis of 1,2,4-benzotriazines

“…Bis-1,2,4-benzotriazines (144) have significant antibacterial activities. To account for the formation of (142) from reaction of ( 139) with ( 140), the mechanism suggested that the reaction proceeded through the initial formation of the respective intermediate (141) followed by in situ cyclization with concurrent elimination of water molecules to give the product (142). This is most likely a redox reaction through the o-quinone or p-quinoid oxidation stage, presumably oxidative ipso-attack on the carbon carrying the methoxy group, elimination of methanol and subsequent reduction to restore the initial oxidation stage.…”

“…This is most likely a redox reaction through the o-quinone or p-quinoid oxidation stage, presumably oxidative ipso-attack on the carbon carrying the methoxy group, elimination of methanol and subsequent reduction to restore the initial oxidation stage. Consequently, the reaction of compound (142) with (140) led to the formation of intermediate (143), where hydrolysis of one of the methoxy groups occurred, followed by in situ cyclization under elimination of water to give the symmetrical bis-adducts (144) (Scheme 24). First, the product was nitrated to 4-nitro-2,2'-bipyridine 1-oxide (147) and further oxidation with m-CPBA gave the corresponding bis-N-oxide.…”