Lanthanide (Ln) complexes have been widely used in biological imaging and functional materials due to their attractive optoelectronic and magnetic properties. Strongly absorbing ligand scaffolds such as conjugated macrocycles are of great interest for Ln complex construction, for the maintaining solution stability, preventing coordination of quenching moieties and serving as antennas.¹ Porpholactones, in which one porphyrin b,b′-double bond replaced by a lactone moiety, could be potent candidate to further increase NIR emission of lanthanides.^2,3 In this talk, we will report the synthesis and characterization of a series of Ln porpholactones as well as their photophysical properties. The lactonization of beta-periphery of porphyrins renders the lower triplate excited states compared to those in porphyrins, which enhances the NIR emission of Ln ions.⁴ More importantly, through beta-fluorination of porphyrin periphery, the life time of NIR emission is significantly increased, which is considered to block the non-irradtive pathway. Taken together, the beta-modification of porphyrin represent an effective approach to enhance the NIR emission of Ln ions, which has the potential to further improve the practical application of Lanthanide chemistry.4 

References:

1. V. Bulach, F. Sguerra, M. W. Hosseini, Coord. Chem. Rev. 2012, 256, 1468–1478;

2. Xian-Sheng Ke, Hongmei Zhao, Xiaoran Zou, Yingying Ning, Xin Cheng, Hongmei Su*, and Jun-Long Zhang* ,J. Am. Chem. Soc., 2015, 137, 10745-10752

3. Xian-Sheng Ke, Yi Chang, Jia-Zhen Chen, Jiangwei Tian, John Mack, Xin Cheng, Zhen Shen* and Jun-Long Zhang*, J. Am. Chem. Soc., 2014, 136, 9598-9607;

4. Xian-Sheng Ke, Bo-Yan Yang, Xin Cheng, Sharon Lai-Fung Chan, and Jun-Long Zhang*, Chem. Eur. J., 2014, 20, 4324-4333;

5. Data unpublished.