Solvent-Directed Transformation of the Self-assembly and Optical Property of a Peptide-Appended Core-Substituted Naphthelenediimide and Selective Detection of Nitrite Ions in an Aqueous Medium

Abstract

This study vividly displays the different self-assembling behavior and consequent tuning of the fluorescence property of a peptide-appended core-substituted naphthalenediimide (N1) in the aliphatic hydrocarbon solvents (n-hexane/n-decane/methyl cyclohexane) and in an aqueous medium within micelles. The N1 is highly fluorescent in the monomeric state and self-aggregates in a hydrocarbon solvent, exhibiting “H-type” or “face-to-face” stacking as indicated by a blue shift of absorption maxima in the UV–vis spectrum. In the H-aggregated state, the fluorescence emission of N1 changes to green from the yellow emission obtained in the monomeric state. In the presence of a micelle-forming surfactant, cetyl trimethylammonium bromide (CTAB), the N1 is found to be dispersed in a water medium. Interestingly, upon encapsulation of N1 into the micelle, the molecule alters its self-assembling pattern and optical property compared to its behavior in the hydrocarbon solvent. The N1 exhibits “edge-to-edge” stacking or J aggregates inside the micelle as indicated by the UV–vis spectroscopic study, which shows a red shift of the absorption maxima compared to that in the monomeric state. The fluorescence emission also differs in the water medium with the NDI derivative exhibiting red emission. FT-IR studies reveal that all amide NHs of N1 are hydrogen-bonded within the micelle (in the J-aggregated state), whereas both non-bonding and hydrogen-bonding amide NHs are present in the H-aggregated state. This is a wonderful example of solvent-mediated transformation of the aggregation pattern (from H to J) and solvatochromism of emission over a wide range from green in the H-aggregated state to yellow in the monomeric state and orangish-red in the J-aggregated state. Moreover, the J aggregate has been successfully utilized for selective and sensitive detection of nitrite ions in water even in the presence of other common anions (NO3 –, SO4 2–, HSO4 –, CO3 2–, and Cl–).

Self-Assembly, Bioactivity, and Nanomaterials Applications of Peptide Conjugates with Bulky Aromatic Terminal Groups

“…These form organogels with a fibrillar structure with J-type aggregates, and undergo aggregation-driven changes in fluorescence, as well as having interesting conductivity behavior . A core-substituted NDI shown in Figure shows solvatochromism, with different colors in different solvents . In addition, there is a notable change in fluorescence color in the presence of micelles of cetyltrimethylammonium bromide (due to a change in molecular packing) and finally in water the fluorescence intensity can be used as a sensitive probe of nitrite ions, even in the presence of other anions …”

A March to Shape Optical Artificial Olfactory System toward Ultrasensitive Detection of Improvised Explosives

“…From the research on optical detection of IEs from 2010 to 2021 ( Figure ), it can be found that the detection limits of hypochlorite, [ 41–57 ] perchlorate, [ 58–60 ] peroxide, [ 61–77 ] nitrate, [ 78–85 ] and nitrite [ 86–99 ] based on solution reaction are mostly between 10 −5 and 10 −9 M , and it is difficult to achieve higher sensitivity detection by merely optical probes designing. By combining the sensing probes with paper‐based [ 19,100–103 ] and hydrogel‐based [ 28,104–106 ] substrate and optical microscope device, the detection sensitivity has been greatly improved in 2020 and 2021 reaching a level of 10 −15 M. To better improve the detecting sensitivity, optical artificial olfactory system takes chemical sensor array as the detection modules of different IEs, as well as considering the automatic analyte collection with airflow and the ultrasensitive ecognition of optical signals has been explored from the design of different components.…”

“…Researches on optical detection of hypochlorite, [ 41–57 ] perchlorate, [ 58–60 ] peroxide, [ 61–77 ] nitrate, [ 78–85 ] and nitrite [ 86–99 ] IEs from 2010 to 2021 and sensors with paper‐based [ 19,100–103 ] and hydrogel‐based [ 28,104–106 ] substrate and optical microscope device. The first Figure from left on bottom reproduced with permission.…”

“…The second Figure from left on bottom reproduced with permission. [ 98 ] Copyright 2021, Elsevier. The third Figure from left on bottom reproduced with permission.…”

“…Copyright 2021, Elsevier. The second Figure from left on bottom reproduced with permission [98]. Copyright 2021, Elsevier.…”