Systematic Design of a Low-Molecular-Weight Gelator and Its Application in the Sensing and Retention of Residual Antibiotics

Abstract

This work presents stepwise design and synthesis of a set of amide-based compounds, L1−L3, assisted by the crystal engineering approach. Out of the three compounds, L3 successfully acted as a low-molecular-weight gelator (LMWG) and formed a gel that was characterized using an array of spectroscopic, rheological, and microscopic imaging techniques. LMWG L3 was used for the nanomolar sensing of a few antibiotics while it also formed stable gel with them. The L3@antibiotic gel was found to hold an antibiotic effectively within its fibrous network, thus creating potential opportunities for the removal of residual antibiotics from contaminated sources.

Selective Detection of Picric Acid and Pyrosulfate Ion by Nickel Complexes Offering a Hydrogen-Bonding-Based Cavity

“…For the detection of nitroaromatics, a solution of nitrobenzene (NB), phenol, benzoic acid (BA) cyclotrimethylenetrinitramine (RDX), 1,3-dinitrobenzene ( The detection limit 35−48 was calculated by using eq 1, where σ is the standard deviation of 10 blank emission measurements of nickel complexes 1−3 and k is the slope of a plot of emission of complexes 1−3 versus [picric acid]. The binding constant (K b ) was determined from the ratio of intercept and slope of the straight line of the Benesi−Hildebrand plot [35][36][37][38][39][40][41][42][43][44][45][46][47][48]93 of 1/(I − I 0 ) versus 1/[PA] (eq 2), where I 0 and I are the emission of complexes 1−3 in absence and in the presence of PA, respectively, and I min is the minimum emission in the presence of PA. (quinine sulfate, Φ st = 0.54). A st and A u denote the absorbance of the standard and the sample, respectively.…”

“…26 Similarly, many chemosensors based on organic molecules have been developed for the anion recognition, 27−31 but the utilization of well-defined coordination complexes as the effective and sensitive chemosensors has been comparatively underexplored. 32−34 Our group has been working on developing various chemosensors for the selective detection of cations, 35−40 anions, 41,42 gases, 38,41,42 drugs, 43,44 and explosives. 45,46 We have developed both organic molecules 35−42 and cavity-based metal complexes 43−46 as well as coordination polymer (CP)based chemosensors.…”

“…We propose that the H-bonding from the protonated heterocyclic rings assisted in bringing a molecule of PA closer to the nickel center and aided in its coordination to the nickel center (Scheme 2). 44,45,76 In the case of detection of the S 2 O 7 2− ion by complexes 1−3, a clear transparent solution resulted. In fact, a blue-shift was initially observed in the UV−vis spectra of 1−3 after the addition of the pyrosulfate ion while the final spectra suggested the presence of the respective free ligand (Figure S41).…”

Supramolecular Hydrogels: Design Strategies and Contemporary Biomedical Applications

“…[112] As a result, LMWG gels have been investigated for applications such as intelligent drug release depots [113] or delivery vehicles [114,115] and molecular sensors. [116] A large number of gelators exhibit at least one stereogenic centre, and chirality has been observed to play a significant role in gelation. [117] Mixtures of enantiomers are known to self-sort and form separate crystal structures where there is a preference over the formation of a racemic crystal.…”

“…In spite of this, the modification of LMWGs enables the precise tuning of gel properties, as minor molecular alterations or changes in conformation often translate to large physical changes at the macroscale [112] . As a result, LMWG gels have been investigated for applications such as intelligent drug release depots [113] or delivery vehicles [114,115] and molecular sensors [116] …”