Facile synthesis and systematic investigations of a series of novel bent-shaped two-photon absorption chromophores based on pyrimidine.
The synthesis, structure, and single- and two-photon spectroscopic properties of a series of pyrimidine-based (bent-shaped) molecules are reported. All these stable heterocyclic compounds are fully characterized, and exhibit intense single- and two-photon excited fluorescence (SPEF and TPEF) over a wide spectral range from blue to red, with the spectral peak position of the SPEF being basically the same as that of the TPEF. The well-conjugated pi-systems, observed from the crystal structure, indicate the charge transfer feature of the ground state. Meanwhile, the theoretical and experimental studies indicate that the charge transfer from donor to acceptor is greatly enhanced in the excited states and the different substituted donor groups on the pyrimidine have a large effect on the optical and electrochemical properties. Based on typical structure data and comprehensive spectral data, the following structure-property relationships can be determined: for such bent-shaped chromophores, the absorption and the fluorescence wavelength maximum of the SPEF and TPEF, and two-photon absorption cross sections show a similar trend with increasing electron-donating strength of the corresponding terminal group and the number of branches, while the average bond lengths of the pi-linkage and HOMO-LUMO energy levels show an inverse trend. Experimental data and theoretical calculation provide a coherent picture. With these findings, bent-shaped quadrupolar chromophores combining peak TPA cross sections (up to 2280 GM), broad TPA bands throughout the whole 700-900 nm range, and high fluorescence quantum yields could, thus, be obtained. Such compounds are of particular interest for TPEF microscopy, as well as optical data storage in the visible and NIR regions. A data recording experiment proved the potential application of these materials.
Li
Lin
L
Department of Chemistry, Key Laboratory of Functional Inorganic Materials of Anhui Province, Anhui University, Hefei 230039, P.R. China.
Tian
Yu-Peng
YP
Yang
Jia-Xiang
JX
Sun
Ping-Ping
PP
Wu
Jie-Ying
JY
Zhou
Hong-Ping
HP
Zhang
Sheng-Yi
SY
Jin
Bao-Kang
BK
Xing
Xiao-Juan
XJ
Wang
Chuan-Kui
CK
Li
Ming
M
Cheng
Guang-Hua
GH
Tang
Huo-Hong
HH
Huang
Wen-Hao
WH
Tao
Xu-Tang
XT
Jiang
Min-Hua
MH