“…As an alternative of these methods, a colorimetry has attractive advantages of high selectivity, sensitivity, simplicity, convenient procedure and quick analysis time . Hence, the colorimetry has drawn much attention and many colorimetric chemosensors have been reported for detecting Fe 2+ or Fe 3+ or both of them . However, selective colorimetric chemosensors for only Fe 2+ were very rare, and in pure aqueous solution, only four colorimetric chemosensors for Fe 2+ were reported, based on pyridine, picoline, cap‐type, and terpyridine .…”