However, from 210 K, the trend was reversed, where the peak intensity is increased as the increase of temperature. Such phenomenon is associated with a blue shift into the UV region. Compound 2 present a similar phenomenon. From 77 K to 180 K, the peak intensity dropped constantly, while from 210 K to 300 K, the peak intensity gradually increased. Such a reversed correlation between the intensity of the absorption peaks and temperature is likely originated from temperature induced structural changes.