Crystal system: monoclinic
| a: | 45.062 (±0.009) Å |
| b: | 9.5432 (±0.0019) Å |
| c: | 15.205 (±0.003) Å |
| α: | 90° |
| β: | 97.92 (±0.03)° |
| γ: | 90° |
Starting materials: PbBr2(98%), 1-methylpiperazine (99%), hydrobromic acid (ACS reagent, 48%)
Product: Colorless crystals
Description: Dissolve 1.10 g (3 mmol) of PbBr2 in 4 mL of HBr under heating and stirring at 122 °C (A). Add 1 mL of HBr into a separate vial of 1-methylpiperazine (200 mg, 2 mmol). Add the protonated 1-methylpiperazine solution into A under heating for 2 min and cool to room temperature.
Method: Single-crystal X-ray diffraction
Description: Data were collected using either an STOE IPDS 2 or IPDS 2T diffractometer with graphite-monochromatized Mo Kα radiation (λ = 0.71073 Å) (50 kV/40 mA) under N2 at 293 K. Post-processing using STOE X-AREA programs.
Comment: three-layered 2D, refer to S4 Table S3. CIF file available at DOI link.
Crystal system: monoclinic
| Band gap (optical, diffuse reflectance), eV |
|---|
Starting materials: PbBr2(98%), 1-methylpiperazine (99%), hydrobromic acid (ACS reagent, 48%)
Product: Colorless crystals
Description: Dissolve 1.10 g (3 mmol) of PbBr2 in 4 mL of HBr under heating and stirring at 122 °C (A). Add 1 mL of HBr into a separate vial of 1-methylpiperazine (200 mg, 2 mmol). Add the protonated 1-methylpiperazine solution into A under heating for 2 min and cool to room temperature.
Method: Diffuse reflectance spectroscopy
Description: First, perform optical diffuse reflectance using a Shimadzu UV-3600 UV−vis−NIR spectrometer operating in the 200−1000 nm region. Convert reflectance to absorption according to the Kubelka−Munk equation to estimate the band gap.
Comment: Refer to Table 1.
Crystal system: monoclinic
| Photoluminescence peak position, eV |
|---|
Starting materials: PbBr2(98%), 1-methylpiperazine (99%), hydrobromic acid (ACS reagent, 48%)
Product: Colorless crystals
Description: Dissolve 1.10 g (3 mmol) of PbBr2 in 4 mL of HBr under heating and stirring at 122 °C (A). Add 1 mL of HBr into a separate vial of 1-methylpiperazine (200 mg, 2 mmol). Add the protonated 1-methylpiperazine solution into A under heating for 2 min and cool to room temperature.
Method: Steady-state photoluminescence
Description: Excite with 330 nm photons produced from an optical parametric amplifier, which is pumped by a Ti:sapphire amplifier with 800 nm output at 2 kHz repetition rate. Time-integrated photoluminescence spectra were captured with a CCD camera; time-resolved PL spectra were captured with a streak camera.
Comment: Refer to Table 2.