1. Department of Chemistry, Sungkyunkwan University, Suwon 16419, Korea
2. Department of Earth Systems and Environmental Sciences, Chonnam National University, Gwangju 61186, Korea
3. Laboratory of Nuclear Magnetic Resonance, NCIRF, Seoul National University, Seoul 08826, Korea
4. Department of Chemistry Education, Chonnam National University, Gwangju 61186, Korea