*2.1. Materials*

Gd(CH3CO2)3·xH2O (99.9%), Nd(CH3CO2)3·xH2O (99.9%), Y(CH3CO2)3·xH2O (99.9%), Yb(CH3CO2)3·xH2O (99.9%), Tm(CH3CO2)3·xH2O (99.9%), NaOH (>98%), NH4F (>98%), chloroform(99.9%), oleic acid (OA, 90%), and 1-octadecene (ODE, 90%) were all purchased from Sigma-Aldrich (Shanghai, China). IR-806 is supported by Dr. Sanyang Han from the University of Cambridge. IR-780 iodide, 4-mercaptobenzoic acid, and N,Ndimethylformamide (DMF, anhydrous, 99.8%), as raw materials of IR-806, were obtained from Sigma-Aldrich (London, UK). Dichloromethane (DCM, AR) and diethyl ether (AR), as solvents for the synthesis of IR-806, were obtained from Lab-Scan (London, United Kingdom). Chloroform (AR), cyclohexane (AR), and ethanol (AR) were purchased from Sinopharm Chemical Reagent Co., Ltd. (Shanghai, China). All chemicals and reagents were used as received without further purification unless otherwise noted.
