title: Structural and photophysical properties of HPPCO (4-hydroxy-5-phenyl-6H-pyrido[3,2,1-jk]carbazol-6-one) derivatives.
abstract: Proton-substitution effects of 4-hydroxy-5-phenyl-6H-pyrido[3,2,1-jk]carbazol-6-one (HPPCO) on structural and photophysical properties were presented. HPPCO crystallized in the orthorhombic space group Pbca with an intermolecular hydrogen bonding between OH and oxygen atom of the carbonyl. The proton-substituted derivatives, 6-oxo-5-phenyl-6H-pyrido[3,2,1-jk]carbazol-4-yl acetate (OPPCA) and 6-oxo-5-phenyl-6H-pyrido[3,2,1-jk]carbazol-4-yl benzoate (OPPCB), crystallized in the monoclinic P2₁/c space group. For OPPCA and OPPCB, a weak interaction between carbonyl oxygen atom in the substituted group and carbon atom in the fused ring was responsible for three-dimensional arrangements. In addition, 6-oxo-5-phenyl-6H-pyrido[3,2,1-jk]carbazol-4-yl furan-2-carboxylate (OPPCF), and 6-oxo-5-phenyl-6H-pyrido[3,2,1-jk]carbazol-4-yl naphthoate (OPPCN) were also synthesized. HPPCO and the four derivatives excited by ultraviolet (UV) light produced blue emission. Proton substitution of the OH group significantly increased the radiative transitions and moderately decreased the non-radiative transitions. Consequently the luminescence quantum yields of the derivatives enhanced more than 4.6-fold, no matter what the groups were substituted. Structural and optical properties were further determined using density functional theory (DFT) and ZINDO calculations. The planar structure of the pyridocarbazole-fused ring resulted in π→π(*) electronic transitions within the main frame, with an additional transition from the n(O) of carbonyl to the π(*) of the main frame. The three excited states that arose from these transitions were responsible for the blue luminescence.
authors.affiliation: Department of Chemistry, Chungnam National University, Daejeon 305-764, Republic of Korea.
authors.forename: Yong-Kwang
authors.initials: YK
authors.lastname: Jeong
authors.affiliation: Department of Chemistry, Chungnam National University, Daejeon 305-764, Republic of Korea.
authors.forename: Min-Ah
authors.initials: MA
authors.lastname: Kim
authors.affiliation: Department of Chemistry, Chungnam National University, Daejeon 305-764, Republic of Korea.
authors.forename: Hyo-Sung
authors.initials: HS
authors.lastname: Lee
authors.affiliation: Department of Chemistry, Chungnam National University, Daejeon 305-764, Republic of Korea.
authors.forename: Jong-Moon
authors.initials: JM
authors.lastname: Kim
authors.affiliation: Center for Research Facilities, Chungnam National University, Yuseong-gu, Daejeon 305-764, Republic of Korea.
authors.forename: Sung Woo
authors.initials: SW
authors.lastname: Lee
authors.affiliation: Department of Chemistry, Chungnam National University, Daejeon 305-764, Republic of Korea. Electronic address: jgkang@cnu.ac.kr.
authors.forename: Jun-Gill
authors.initials: JG
authors.lastname: Kang
mesh_terms: D002227:Carbazoles / Q000737:chemistry*; D060326:Chemistry Techniques, Synthetic; D018360:Crystallography, X-Ray; D008163:Luminescent Measurements / Q000379:methods*; D008956:Models, Chemical; D008958:Models, Molecular; D015394:Molecular Structure; D011522:Protons; D011725:Pyridines / Q000737:chemistry*; D013329:Structure-Activity Relationship
chemical_list: C000601615:4-hydroxy-5-phenyl-6H-pyrido(3,2,1-jk)carbazol-6-one; D002227:Carbazoles; D011522:Protons; D011725:Pyridines
keywords: DFT and CIS calculations; Highly enhanced luminescence; Pyridocarbazole derivatives; X-ray structure