Synthesis of a Porous C3N-Derived Framework with High Yield by Gallic Acid Cross-Linking Using Salt Melts

Porous carbon/nitrogen frameworks are an emerging class of noble organic materials with a wide range of potential applications. However, the design and controlled synthesis of those materials are still a challenge. Herein, we present the rational design of such a system with high microporosity, specific surface areas of up to 946 m2 g–1, and excellent condensation yields. The obtained noble frameworks were used for the delivery of larger organic molecules and changed the melting behavior of some daily drug molecules along their highly polarizable surfaces.

Materials Synthesis 5 mmol gallic acid, 5 mmol 2,3-diaminophenazine, and ZnCl2 (in a weight ratio of precursor: salt of 1:10) were mixed in a 100 mL flask in the inert N2 atmosphere.
Subsequently, the mixture was continuously heated to different temperatures (300, 350, 400, 450, 500, and 550 o C) for 3 h (the 850 o C sample was prepared in an oven in the inert N2 atmosphere). After cooling down to room temperature, the resulting black carbon/salt product was stirred in deionized water for 15 h and 1 M HCl for 15 h. Then the product was filtered, washed with water and ethanol, and dried in vacuum at 80 o C for 24 h.
All samples are referred to as GD-X, X is the preparation temperature.
The D-500 was made by the same method as GD-500 without the precursor gallic acid.

Materials characterization
Fourier transformed infrared (FTIR) spectra were recorded by a Varian 600 FTIR spectrometer. Thermogravimetric analysis (TGA) was obtained using a NETZSCHTG 209 F1 device, in an air flow with a heating rate of 5 o C min -1 . Scanning electron microscopy (SEM) was performed using a LEO 1550-Gemini microscope. Prior investigation, a thin (~15 nm) layer of platinum was applied on top of the sample to increase conductivity. Energydispersive X-ray (EDX) investigations were conducted by a Link ISIS-300 system (Oxford Microanalysis Group). X-ray diffraction patterns (XRD) were investigated on a Bruker D8 Advance instrument with Cu-Kα radiation. High-resolution transmission electron microscopy (HRTEM) was observed on a double-Cs-corrected JEOL ARM 200F instrument operated at 200 kV. Elemental analysis was measured on a Vario Micro device. X-ray photoelectron spectroscopy (XPS) was recorded with a Thermo Scientific K-Alpha + X-ray Photoelectron Spectrometer.
Pore structure properties of the materials were measured via nitrogen adsorption and desorption at 77 K using a volumetric technique on a Quantachrome Quadrasorb SI porosimeter. Prior to analysis, the samples were degassed under vacuum at 150 o C for 20 h.
Total pore volume (Vt) was determined from the amount of nitrogen adsorbed at P/P0 = 0.995.
The pore size distributions of the samples were obtained by quenched solid Density Functional Theory (QSDFT) model with slit/cylindrical pore shape using nitrogen adsorption branch kernel. Ar physisorption was measured at 87 K. The pore size distribution was calculated using QSDFT method (adsorption branch kernel) for Ar adsorbed on carbon with cylindrical/sphere pore shape at 87 K.

DSC test
Before the fabrication process for the composites, GD-500 was degassed under vacuum at 250 o C for 20 h.
Acetic acid/carbon composites: 0.03 g acetic acid was dropped into 0.05 g GD-500 powder, then the residual gas in the pore of the carbon was removed by pulling a vacuum for 1 h. Naphtalene, HCOONH4, Aspirin/carbon composites: 0.03 g Naphtalene, HCOONH4, and aspirin were first dissolved in ethanol (0.15 ml), respectively. Then, 0.05 g GD-500 was added into the solution. After the ultrasonic for 3 h, the mixed ink was dried at 80 o C for 24 h in an oven to remove the ethanol.
Q10, Wax/carbon composites: 0.03 g Q10 or wax were mixed with 0.05 g GD-500. Then, the Q10, Wax/carbon mixture was heated to 53 o C and 70 o C under vacuum for 2 h.
The calorimetric experiments were conducted using a NETZSCH TG 209 F1 instrument.

Aspirin release study
The aqueous release of pure aspirin and aspirin loaded GD-500 sample was determined in purified water at a temperature of 25 o C. Briefly, 30 mg aspirin or 80 mg of aspirin loaded GD-500 (equivalent to 30 mg aspirin) were put into dialysis bags. After adding 1 mL of water to the bags, they were clamped with a clip and put into 40 mL water baths. 0.5 mL samples were collected from the bath solution at defined time intervals (5,10,15,20,30,45 Table S1. Textural properties of the samples.