Dinuclear Lanthanide(III)-m-ODO2A-dimer Macrocyclic Complexes: Solution Speciation, DFT Calculations, Luminescence Properties, and Promoted Nitrophenyl-Phosphate Hydrolysis Rates

C Allen Chang; Hwa-Yu Lee; Syue-Liang Lin; Ching-Ning Meng; Tsung-Ta Wu

doi:10.1002/chem.201800037

Dinuclear Lanthanide(III)-m-ODO2A-dimer Macrocyclic Complexes: Solution Speciation, DFT Calculations, Luminescence Properties, and Promoted Nitrophenyl-Phosphate Hydrolysis Rates

Chemistry. 2018 Apr 25;24(24):6442-6457. doi: 10.1002/chem.201800037. Epub 2018 Apr 14.

Authors

C Allen Chang^{1

2

3

4}, Hwa-Yu Lee¹, Syue-Liang Lin², Ching-Ning Meng¹, Tsung-Ta Wu⁴

Affiliations

¹ Department of Biomedical Imaging and Radiological Sciences, National Yang-Ming University, No. 155, Sec. 2, Li-Nong St., Beitou, Taipei, Taiwan), 112, Republic of China.
² Department of Biotechnology and Laboratory Science in Medicine, National Yang-Ming University, No. 155, Sec. 2, Li-Nong Street, Taipei, 112, Taiwan, Republic of China.
³ Molecular Imaging Research Center (MIRC), National Yang-Ming University, Taipei, 112, Taiwan, Republic of China.
⁴ Department of Biological Science and Technology, National Chiao Tung University, No. 75 Po-Ai Street, Hsinchu, Taiwan, 30039, Republic of China.

PMID: 29479746
DOI: 10.1002/chem.201800037

Abstract

Potentiometric speciation studies, mass spectrometry, and DFT calculations helped to predict the various structural possibilities of the dinuclear trivalent lanthanide ion (Ln^III , Ln=La, Eu, Tb, Yb, Y) complexes of a novel macrocyclic ligand, m-ODO2A-dimer (H₄ L), to correlate with their luminescence properties and the promoted BNPP and HPNP phosphodiester bond hydrolysis reaction rates. The stability constants of the dinuclear Ln₂ (m-ODO2A-dimer) complexes and various hydrolytic species confirmed by mass spectrometry were determined. DFT calculations revealed that the Y₂ LH_-1 and the Y₂ LH_-2 species tended to form structures with the respective closed- and open-form conformations. Luminescence lifetime data for the heterodimetallic TbEuL system confirmed the fluorescence resonance energy transfer from the Tb^III to Eu^III ion. The internuclear distance R_TbEu values were estimated to be in the range of 9.4-11.3 Å (pH 6.7-10.6), which were comparable to those of the DFT calculated open-form conformations. Multiple linear regression analysis of the k_obs data was performed using the equation: k_obs,corr. =k_obs -k_obs,OH =kLn2LHM->1 [Ln₂ LH_-1 ]+kLn2LH-2 [Ln₂ LH_-2 ] for the observed Ln₂ L-promoted BNPP/HPNP hydrolysis reactions in solution pH from 7 to 10.5 (Ln=Eu, Yb). The results showed that the second-order rate constants for the Eu₂ LH_-2 and Yb₂ LH_-2 species were about 50-400 times more reactive than the structural analogous Zn₂ (m-12 N₃ O-dimer) system.

Keywords: DFT calculations; bond hydrolysis; lanthanide complexes; luminescence; stability and speciation.