title: Conformations of substituted benzophenones.
abstract: The inclination of the two aryl rings (ring twists) in a series of benzophenone molecules has been examined. For each structure the dihedral angle (between the planes of the two sets of six aromatic C atoms) relates to both the steric considerations of the single molecule and the packing forces related to the crystal structure. Six new benzophenone structures are incorporated into the study including 2,2'-dihydroxy-4,4'-dimethoxybenzophenone (I), C(15)H(14)O(5), that appears to have the smallest reported twist angle, 37.85 (5) degrees , of any substituted benzophenone reported to date. Three further benzophenones, 4,4'-bis(diethylamino)benzophenone (II), C(21)H(28)N(2)O, 3,4-dihydroxybenzophenone (III), C(13)H(10)O(3), and 3-hydroxybenzophenone (IV), C(13)H(10)O(2), have similar ring twists [49.83 (5), 49.84 (5) and 51.61 (5) degrees , respectively] that are comparable with the value of 54 degrees found for the orthorhombic form of unsubstituted benzophenone. 4-Chloro-4'-hydroxybenzophenone (V), C(13)H(9)ClO(2), has a ring twist of 64.66 (8) degrees that is close to the value of 65 degrees found in the metastable monoclinic form of unsubstituted benzophenone and 2-amino-2',5-dichlorobenzophenone (VI), C(13)H(9)Cl(2)NO(2), has a large ring twist of 83.72 (6) degrees . Comparisons with a further 98 substituted benzophenone molecules from the Cambridge Structural Database (CSD) have been made.
authors: The Robert Gordon University, Schoolhill, Aberdeen AB10 1FR, Scotland. p.j.cox@rgu.ac.uk
authors: Philip J
authors: PJ
authors: Cox
authors: Dimitrios
authors: D
authors: Kechagias
authors: Orla
authors: O
authors: Kelly
mesh_terms: D001577:Benzophenones / Q000737:chemistry* / Q000528:radiation effects; D018360:Crystallography, X-Ray; D006860:Hydrogen Bonding; D008968:Molecular Conformation; D015394:Molecular Structure; D011837:Radiation-Protective Agents / Q000737:chemistry / Q000528:radiation effects; D013473:Sunscreening Agents / Q000737:chemistry / Q000528:radiation effects; D014466:Ultraviolet Rays / Q000009:adverse effects
chemical_list: D001577:Benzophenones; D011837:Radiation-Protective Agents; D013473:Sunscreening Agents