Comparison of two pyrazole derived “turn on” fluorescent probes for the recognition of Ga3+

Thienopyrimidine‐derived multifunctional fluorescence sensor for the detection of Cu2+, Fe3+, and PPi in different solvents

“…As shown in Figure 13, R1 exhibited predominantly negative electrostatic potential at thiopyrimidine, which was attributed to the effects of the surrounding electric fields, resulting in strong nucleophilicity. After the addition of Cu 2+ , the whole molecule of R1 ‐Cu 2+ was greatly influenced by the nucleus of Cu 2+ , and the positive electrostatic potential of the whole molecule revealed the tendency of R1 to form stable Cu 2+ complexes [51]. In addition, under the joint influence of the Fe 3+ nucleus and conjugated system, R1 ‐Fe 3+ showed a relatively obvious positive and negative split after binding with Fe 3+ .…”

“…As Figure S17 shows, the peak that emerged at 587.6692 m/ z was assigned to [R1 + 2Fe 3+ ], which was consistent with the result above. So, based on the above experimental dates and relevant reports, possible binding modes were proposed in Scheme 2 [48,49] plexes [51]. In addition, under the joint influence of the Fe 3+ nucleus and conjugated system, R1-Fe 3+ showed a relatively obvious positive and negative split after binding with Fe 3+ .…”

“…Due to the uneven accumulation of electrons in these regions, part of the intramolecular energy was expressed in the form of fluorescence emission, leading to bluegreen fluorescence. However, noticeable fluorescence quenching was produced with the introduction of Cu 2+ and Fe 3+ , resulting from the paramagnetism of these two metals[50,51]. Electrons cluster around Cu 2+ and Fe 3+ , and the electron densities of the triphenylamine group and thiophene ring were reduced, which brought about the fluorescence 'off' state.…”

Robust Optical Detection of Ga3+ by a Rhodamine- and Coumarin-Based Proficient Probe: Theoretical Investigations and Biological Applications

“…It is well-known that detection methods are expanding rapidly worldwide, but the use of fluorescent techniques for the detection of analytes is always ahead of other techniques and has become a hot subject in chemical research due to its high sensitivity, selectivity, affordability, and ease of use. − Schiff-base ligands with potential fluorophores and extended conjugation are mainly used to detect Ga 3+ because of their far absorption and emission properties and the formation of the geometric cavity for chelation. − One more important factor is the selectivity, which is lacking in many chemosensors due to their multiple detection ability for many group 13 metal ions. − In group 13, the size of the Al is more than Ga due to the well-known d-contraction in Ga (poor shielding effect of the 3d-electrons). Therefore, having hard donor sites with comparatively smaller cavity sizes prefers Ga 3+ more prominently over Al 3+ .…”