Ureidobenzotriazine multiple H-bonding arrays: the importance of geometrical details on the stability of H-bonds.
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 A) 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.
Laboratory of Macromolecular and Organic Chemistry, Eindhoven University of Technology, P.O. Box 513, 5600 MB, Eindhoven, The Netherlands.
G B W L
GB
Ligthart
Dawei
D
Guo
A L
AL
Spek
Huub
H
Kooijman
Han
H
Zuilhof
Rint P
RP
Sijbesma
D003198:Computer Simulation; D018360:Crystallography, X-Ray; D006860:Hydrogen Bonding; D008956:Models, Chemical; D008958:Models, Molecular; D015394:Molecular Structure; D011789:Quantum Theory; D014227:Triazines / Q000138:chemical synthesis / Q000737:chemistry*; D014529:Uridine / Q000031:analogs & derivatives* / Q000138:chemical synthesis / Q000737:chemistry
C527311:3-ureidobenzo-1,2,4-triazine 1-N-oxide; D014227:Triazines; D014529:Uridine