Crystal system: hexagonal
| Band gap (optical, diffuse reflectance), eV |
|---|
Starting materials: distilled HI (aqueous 99.95%), H3PO2 (50% aqueous), SnI2 (synthesized from Sn granules, and I2 (99.8%)), CH3C(NH2)2I (synthesized from CH3C(NH2)2Cl (95%) and HI)
Product: orange, hexagonal needles
Description: Two-necked flask was charged with aqueous HI (6.8 mL, 7.58 M) and aqueous H3PO2 (1.7 mL, 9.14 M). Nitrogen was passed through the liquid to degass the solution. SnI2 (372 mg, 1 mmol) was dissolved in solution, and flask was heated to boiling (~130 ºC) via an oil bath. A bright yellow solution formed under magnetic stirring. Solid CH3C(NH2)2I (186 mg, 1 mmol) was added to the solution, and the solution was heated to 120º C. Crystals began to grow and were left to grow at this temperature for 2 hours. Finally, the solution was cooled to room temperature.
Method: UV-vis absorption (diffuse reflectance)
Description: Diffuse-reflectance measurements were performed and collected at room temperature. A Shimadzu UV-3600 PC double-beam and double monochromator spectrophotometer (operating between 200 to 2500 nm) was used.BaSO4 was used as a nonabsorbing reflectance reference. Generated reflectance v. wavelength data was used to estimate the band gap. The Kubelka-Munk equation α/S = (1-R)^{2}/(2R) was used.
Crystal system: monoclinic
| Band gap (optical, diffuse reflectance), eV |
|---|
Starting materials: distilled HI (aqueous 99.95%), H3PO2 (50% aqueous), SnI2 (synthesized from Sn granules, and I2 (99.8%)), CH3C(NH2)2I (synthesized from CH3C(NH2)2Cl (95%) and HI)
Product: red-orange crystals
Description: Two-necked flask was charged with aqueous HI (6.8 mL, 7.58 M) and aqueous H3PO2 (1.7 mL, 9.14 M). Nitrogen was passed through the liquid to degass the solution. SnI2 (744 mg, 2 mmol) was dissolved in solution, and flask was heated to boiling (~130 ºC) via an oil bath. A bright yellow solution formed under magnetic stirring. Solid CH3C(NH2)2I (372 mg, 2 mmol) was added to the solution, and crystals began to grow when stirring was discontinued. Solution cooled, and crystals transformed from red-orange needles to yellow hexagonal plates.
Method: UV-vis absorption (diffuse reflectance)
Description: Diffuse-reflectance measurements were performed and collected at room temperature. A Shimadzu UV-3600 PC double-beam and double monochromator spectrophotometer (operating between 200 to 2500 nm) was used.BaSO4 was used as a nonabsorbing reflectance reference. Generated reflectance v. wavelength data was used to estimate the band gap. The Kubelka-Munk equation α/S = (1-R)^{2}/(2R) was used.