A comparative study between acridine-based macrocycle chemosensor switches to Cd(II): synthesis, spectroscopy, and theoretical calculation

Two Acridone Units in One Crown Ether

“…What is more, the quantum yield of the bisacridono-macrocycle is inferior to that of many analogues containing only one acridone unit [26]. Probably it is due to the increased number of possible vibration modes as observed similarly by dos Santos Carlos et al [16].…”

“…Surprisingly we found, that the main products were the monofunctionalized derivatives (12, 13, 14, respectively) in each case. Although LC-MS studies showed that the expected bifunctionalized products (15)(16)(17) were formed, but their amounts proved to be negligible. Many efforts were made using large excess of reagents (TsCl, MsCl, PBr 5 ) in harder conditions to enhance the conversion of the second hydroxyl group, but only the monohydroxy derivatives (12)(13)(14) could be gained as main products.…”

“…Initially, acridonediol 4 had to be connected with glycols, which would serve as the ether linkers between the two heterocycles of the host. First this reaction was also attempted by using bifunctional ethanes (15)(16)(17) as reagents (see procedure D) in Scheme 1), but the reactions resulted in the corresponding monohydroxy derivatives (12)(13)(14) as main products. Thus, the same reaction was carried out using monoprotected glycol 5 [25], when product 6 was obtained with a medium yield.…”

“…A comparative study, which discussed the complexation and optical signaling ability of the macrocycles as a function of the number of acridine units in the macroring (see 2 in Fig. 2) has recently showed, that in addition to the quite different selectivities, the fluorescence could either not be enhanced by the increasing number of incorporated heterocycles, because the greater number of their possible vibration modes inhibited it [16]. The macrocycles containing NH-groups with aliphatic chains (2 in Fig.…”