Succinic anhydride

All manipulations involving air- and/or water-sensitive compounds were carried out with the standard Schlenk and vacuum line techniques under an argon atmosphere or in a nitrogen-filled glovebox. Succinic anhydride (SA) and citraconic anhydride (CA) were purchased from Macklin. Propylene epoxide (PO) was purchased from Aldrich. Chromatographic purity solvents, including toluene, dichloromethane, tetrahydrofuran (THF), ethanol, and flaky sodium hydroxide (CaH₂), were bought from SINOPHARM. Triethyl borane (TEB) in tetrahydrofuran solution (1.0 mol/L), Dimethyl succinate (DS), and dimethyl citraconate (DC) were purchased from the Tokyo Chemical Industry (TCI). Triethylamine (TEA) was purchased from Aldrich, and 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene (mTBD) and 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) were purchased from TCI. PO, TEA, DBU, DS, DC, and toluene were refluxed over CaH₂ for 24 h and vacuum-distilled prior to use. In particular, chloroform-d for dynamic NMR characterization of amine-ester complexes was refluxed over CaH₂ for 24 h and distilled prior to use. Both the anhydrides (SA and CA) were purified by vacuum sublimation three times. The purified anhydrides were collected under an inert atmosphere and stored in the glovebox for use. Other organic reagents were used without purification.

OA was distilled from Camellia seed oil in our lab with its purity of 98% [31 (link),32 (link)]. PEI with molecular weight ≈10,000, mPEG with molecular weight ≈2000, DOX, succinic anhydride, N-hydroxysuccinimide (NHS), 4-Nitrophenyl Chloroformate, o-nitrobenzyl alcohol, 4-dimethylaminopyridine (DMAP), and 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDC) were purchased from Macklin Reagent Co. (Shanghai, China). Yttrium oxide (Y₂O₃, 99.99%), ytterbium oxide (Yb₂O₃, 99.99%), erbium oxide (Er₂O₃, 99.99%), and sodium fluoride (NaF, 98%) were purchased from Shanghai Chemical Industrial Company (Shanghai, China). Pyrene, 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenytetrazolium bromide (MTT), and 4,6-diamidino-2-phenylindole (DAPI) were purchased from Aladdin Reagent Co. (Shanghai, China). Phosphotungstic acid dye, glutaraldehyde, and copper mesh were purchased from Beijing Zhongjingkeyi Technology Co. (Beijing, China). Human lung adenocarcinoma cells A549 cells and DMEM medium were bought from Shanghai Cell Bank (Shanghai, China). Chloroform, acetonitrile, ethyl ether, and dimethyl sulfoxide (DMSO) were supplied by Sinopharm Chemical Reagent Co. (Shanghai, China). Transparent polystyrene 6-well and 96-well plates were obtained from Corning Co. (Corning, NY, USA).