Endre søk
RefereraExporteraLink to record
Permanent link

Direct link
Referera
Referensformat
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annet format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annet språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf
Crystal Structures of N-Aryl-N′-4-Nitrophenyl Ureas: Molecular Conformation and Weak Interactions Direct the Strong Hydrogen Bond Synthon
University of Hyderabad, School of Chemistry.
University of Hyderabad, School of Chemistry.
University of Hyderabad, School of Chemistry.
Vise andre og tillknytning
2007 (engelsk)Inngår i: Crystal Growth & Design, ISSN 1528-7483, E-ISSN 1528-7505, Vol. 7, nr 12, s. 2675-2690Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

Hydrogen bond competition was studied in 21 X-ray crystal structures of N-X-phenyl-N′-p-nitrophenyl urea compounds (X = H, F, Cl, Br, I, CN, C≡CH, CONH2, COCH3, OH, Me). These structures are classified into two families depending on the hydrogen bond pattern: urea tape structures contain the well-known α-network assembled via N-HO hydrogen bonds; however, in nonurea tape structures the N-H donors hydrogen bond with NO2 groups or solvent O acceptor atoms. Surprisingly, the urea CO hardly accepts strong H bonds in nonurea type structures sustained by ureanitro and ureasolvent synthons. The carbonyl group accepts intra- and intermolecular C-HO interactions. The molecular conformation and H bonding motifs are different in the two categories of structures: the phenyl rings are twisted out of the urea plane in the tape motif, but they are coplanar in the nonurea category. Even though hydrogen bond synthon energy and urea carbonyl acceptor strength favor the N-HO tape structure, the dominant pattern in electron-withdrawing aryl urea crystal structures is the ureanitro/ureasolvent synthon and persistence of intramolecular C-HO interactions. Remarkably, the presence of functional groups that can promote specific C-IO or C-HO interactions with the interfering NO2 group, for example, when X = I, C≡CH, NMe2, and Me, steers crystallization toward the N-HO urea tape structure, and now the diaryl urea molecule adopts the metastable, twisted conformation. Molecular conformer energy calculations and difference nuclear Overhauser enhancement NMR experiments show that the planar, trans-trans-N,N′-diphenyl urea conformation is more stable than the N-Ph twisted rotamer. However, the urea CO is a better hydrogen bond acceptor in the twisted conformer compared to the planar one, based on electrostatic surface potential (ESP) charges. These diaryl ureas together with previously reported crystal structures provide a global structural model to understand how functional groups, molecular conformation, hydrogen bonding, and crystal packing are closely related and influence each other in subtle yet definitive ways. Our strategy simultaneously exploits weak, soft intermolecular interactions and strong, hard hydrogen bonds [supramolecular hard and soft acid-base (HSAB) principle] in the crystal engineering of multifunctional molecules.

sted, utgiver, år, opplag, sider
2007. Vol. 7, nr 12, s. 2675-2690
Identifikatorer
URN: urn:nbn:se:ltu:diva-7257DOI: 10.1021/cg070155jLokal ID: 599c9b50-07ba-11dd-97e0-000ea68e967bOAI: oai:DiVA.org:ltu-7257DiVA, id: diva2:980146
Merknad
Upprättat; 2007; 20080411 (andbra)Tilgjengelig fra: 2016-09-29 Laget: 2016-09-29 Sist oppdatert: 2017-11-24bibliografisk kontrollert

Open Access i DiVA

Fulltekst mangler i DiVA

Andre lenker

Forlagets fulltekst

Personposter BETA

George, Sumod

Søk i DiVA

Av forfatter/redaktør
George, Sumod
I samme tidsskrift
Crystal Growth & Design

Søk utenfor DiVA

GoogleGoogle Scholar

doi
urn-nbn

Altmetric

doi
urn-nbn
Totalt: 39 treff
RefereraExporteraLink to record
Permanent link

Direct link
Referera
Referensformat
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annet format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annet språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf