Mimicking the Natural World with Nanoarchitectonics for Self-Assembled Superstructures.

Scientists are often inspired by nature, where naturally occurring morphologies, such as those that resemble animals and plants, can be created in the lab. In this review, we have provided an overview on complex superstructures of animals, plants and some similar shapes from the natural world. We begin this review with a discussion about the formation of various animal-like shapes from small organic molecules and polymers, and then move onto plants and other selected shapes. Literature surveys reveal that most of the polymers studied tend to form micellar structures, with some exceptions. Nevertheless, small organic molecules tend to form not only micellar structures but also other animal shapes such as worms and caterpillars. These superstructures tend to have high surface areas and variable surface morphology, making them very useful material for applications in various field such as catalysis, solar cells, and biomedicine, amongst others.

Naphthalene diimides: perspectives and promise.

In this review, we describe the developments in the field of naphthalene diimides (NDIs) from 2016 to the presentday. NDIs are shown to be an increasingly interesting class of molecules due to their electronic properties, large electron deficient aromatic cores and tendency to self-assemble into functional structures. Almost all NDIs possess high electron affinity, good charge carrier mobility, and excellent thermal and oxidative stability, making them promising candidates for applications in organic electronics, photovoltaic devices, and flexible displays. NDIs have also been extensively studied due to their potential real-world uses across a wide variety of applications including supramolecular chemistry, sensing, host-guest complexes for molecular switching devices, such as catenanes and rotaxanes, ion-channels, catalysis, and medicine and as non-fullerene accepters in solar cells. In recent years, NDI research with respect to supramolecular assemblies and mechanoluminescent properties has also gained considerable traction. Thus, this review will assist a wide range of readers and researchers including chemists, physicists, biologists, medicinal chemists and materials scientists in understanding the scope for development and applicability of NDI dyes in their respective fields through a discussion of the main properties of NDI derivatives and of the status of emerging applications.

Flower-Like Superstructures: Structural Features, Applications and Future Perspectives.

Mimicking natural objects such as flowers, is an objective of scientists not only because of their attractive appearance, but also to understand the natural phenomena that underpin real world applications such as drug delivery, enzymatic reactions, electronics, and catalysis, to name few. This article reviews the types, preparation methods, and structural features of flower-like structures along with their key applications in various fields. We discuss the various types of flower-like structures composed of inorganic, organic-inorganic hybrid, inorganic-protein, inorganic-enzyme and organic compositions. We also discuss recent development in flower-like structures prepared by self-assembly approaches. Finally, we conclude our review with the future prospects of flower-like micro-structures in key fields, being biomedicine, sensing and catalysis.

Recent Advances in Aggregation-Induced Emission Active Materials for Sensing of Biologically Important Molecules and Drug Delivery System.

The emergence and development of aggregation induced emission (AIE) have attracted worldwide attention due to its unique photophysical phenomenon and for removing the obstacle of aggregation-caused quenching (ACQ) which is the most detrimental process thereby making AIE an important and promising aspect in various fields of fluorescent material, sensing, bioimaging, optoelectronics, drug delivery system, and theranostics. In this review, we have discussed insights and explored recent advances that are being made in AIE active materials and their application in sensing, biological cell imaging, and drug delivery systems, and, furthermore, we explored AIE active fluorescent material as a building block in supramolecular chemistry. Herein, we focus on various AIE active molecules such as tetraphenylethylene, AIE-active polymer, quantum dots, AIE active metal-organic framework and triphenylamine, not only in terms of their synthetic routes but also we outline their applications. Finally, we summarize our view of the construction and application of AIE-active molecules, which thus inspiring young researchers to explore new ideas, innovations, and develop the field of supramolecular chemistry in years to come.

Naphthalenediimide-based nanoarchitectonics for a fluorescent chemosensor with highly selective and sensitive detection of cyanide ions.

A naphthalenediimide (NDI)-based highly potential chemosensor for the detection of cyanide has been synthesized successfully in several steps. The NDI-based probe displayed high selectivity and sensitivity towards cyanide ions in fluorescence 'turn-off' mode over other ions used in this study. The naked-eye, UV-vis absorbance and fluorescence methods are employed to investigate the sensing performance of probe 1 toward CN- ion detection. The limit of detection for CN- ions was calculated to be 4.11 × 10-7 M. Moreover, the Stern-Volmer quenching constant and fluorescence quenching efficiency of CN- ions were estimated to be 1.1 × 105 M and 88.81%, respectively. Job's plot showed a 1 : 1 stoichiometric complexation reaction between probe 1 and CN- ions. For practical applications, probe 1 was efficiently applied for the detection of CN- ions using a paper strip method.

Nanoarchitectonics of neomycin-derived fluorescent carbon dots for selective detection of Fe3+ ions.

The first-ever neomycin antibiotic-based carbon dots (Neo-CDs) were synthesized via a low-cost, eco-friendly, and single-step hydrothermal method using neomycin as a single precursor. The as-prepared Neo-CDs exhibited strong and stable blue fluorescence and were well characterized by TEM, UV-vis absorption, fluorescence emission, IR, XRD, Raman and XPS spectroscopy methods. The Neo-CDs showed a well-distributed size within the range of 4.5 to 7.8 nm, comprising various functional groups on the surface of the carbon core. The Neo-CDs exhibited exceptional emission behaviour, and fluorescence quantum yield was calculated to be 55% in double distilled water. Neo-CDs have been used as a fluorescent sensor for selective and sensitive detection of Fe3+ ions in aqueous solution in the fluorescence turn-off mode. From the set of metal ions, only the Fe3+ ion showed quenching of fluorescence due to photoinduced (PET) electron transfer from Neo-CDs to the half-filled 3d orbital of Fe3+ ions. The limit of detection for Fe3+ ions was calculated to be 0.854 µM. Further, the quenching efficiency and Stern-Volmer quenching constant have been calculated which are about 94% and 5.6 × 106 M-1, respectively.

A New 'Off-On' System Based on Core-Substituted Naphthalene Diimide with Dimethylamine for Reversible Acid-Base Sensing.

A new 'Off-On' system designed and synthesised by functionalisation of a naphthalene diimide (NDI) core with dimethylamine produces 4,9-bis(dimethylamino)-2,7-dioctylbenzo[lmn][3,8]-phenanthroline-1,3,6,8-(2H,7H)-tetraone, abbreviated as DDPT (1). DDPT 1 was synthesised using a simple strategy, namely aromatic nucleophilic substitution using Br2 -NDI with dimethylamine at 110 °C. DDPT was characterized by 1 H and 13 C NMR spectroscopy, ESI mass spectrometry and elemental analysis. DDPT 1 was then used for optical studies through protonation of its dimethylamine core with trifluoroacetic acid (TFA), blue-shifting the absorption band from 600 nm to 545 nm in solution. Interestingly, the fluorescence of DDPT 1 is weak in solution with a quantum yield Φ=0.09, which is significantly enhanced to Φ=0.78 upon addition of TFA. The limit of detection (LOD) was determined to 2.77 nm. Furthermore, DDPT 1 can be used for naked eyed detection not only under UV light (365 nm) but also using visible light, as clear changes can be clearly seen upon addition of TFA. The binding constant of DDPT was calculated to 2.1×10-3  m-1 . Importantly, DDPT 1 showed reversible switching by alternative addition of acid (TFA) and base (triethylamine) without loss of activity. Immobilised on paper, DDPT 1 can be used for strip-test sensing in which the colour changes from blue to reddish when expose to TFA vapours and reverse in the presence of triethylamine vapours.

Aminoglycoside antibiotic kanamycin functionalized tetraphenylethylene molecular probe for highly selective detection of bovine serum albumin protein.

A novel tetraphenylethylene (TPE) functionalized aminoglycoside antibiotic kanamycin (TPE-kana 1) has been successfully synthesized and characterized by means of modern analytical and spectroscopic techniques. The probe TPE-kana 1 showed strong affinity towards bovine serum albumin (BSA) compared to its other biological competitors. The recognition of BSA have been investigated employing UV-Vis absorption and fluorescence emission spectroscopy. The significant color change of TPE-kana 1 with BSA can be observed by necked eye, where the role of AIE-active TPE molecule is handle in both optical and colorimetric changes. The quenching of fluorescence of TPE-kana 1 with BSA was characterized by fluorescence spectroscopy, with 71.16% of quenching efficiency. Moreover, the Stern-Volmer quenching constant was calculated and found to be 2.46 × 107 M-1. Probe TPE-kana 1 showed detection limit of 2.87 nM (nM) towards BSA with binding constant 7.56 × 107 M. A molecular docking study is also performed to investigate the detail interactions between TPE-kana 1 with the sites of BSA via non-covalent i.e., H-bonding, π-cation interactions, π-donor hydrogen bonds and π-π interactions. The lowest binding energy conformation was found at - 10.42 kcal/mol.

Self-assembled kanamycin antibiotic-inorganic microflowers and their application as a photocatalyst for the removal of organic dyes.

Construction of hybrid three-dimensional (3D) hierarchical nanostructures via self-assembly of organic and inorganic compounds have recently attracted immense interest from scientists due to their unique properties and promise in a large range of applications. In this article, hybrid flower structures were successfully constructed by self-assembly an antibiotic, kanamycin, with Cu2+. The flower-like morphology was observed by scanning electron microscopy, to be approximately 4 µm in diameter and about 10 nm in thickness. FTIR spectroscopy and X-ray diffraction confirmed the antibiotic-inorganic hybrid structure was uniform composition, and showed crystallinity due to ordered self-assembly. The hybrid flowers showed high photocatalytic activity towards degradation of methyl blue during 240 minutes under visible light irradiation. A possible mechanism of photocatalytic activity was also proposed, that exposes the inherent advantages in using antibiotic-inorganic hybrid flowers as photocatalysts, where self-assembly can be used to generate active, high surface area structures for photodegradation of pollutants.

The Supramolecular Self-Assembly of Aminoglycoside Antibiotics and their Applications.

Aminoglycosides, a class of antibiotics that includes gentamicin, kanamycin, neomycin, streptomycin, tobramycin and apramycin, are derived from various streptomyces species. Despite the significant increase in the antibacterial resistant pathogens, aminoglycosides remain an important class of antimicrobial drugs due to their unique chemical structure which offers a broad spectrum of activity. The modification of antibiotics and their subsequent use in supramolecular chemistry is rarely reported. Given the importance of aminoglycosides, here we give a brief overview on the modification of 4,5- and 4,6-disubstituted deoxystreptamine classes of aminoglycosides through supramolecular chemistry and their potential for real world applications. We also make the case that the work in this area is gaining momentum, and there are significant opportunities to meet the challenges of modern antibiotics through the modification of aminoglycosides by harnessing the advantages of supramolecular chemistry.

Antenna-like Ring Structures via Self-Assembly of Octaphosphonate Tetraphenyl Porphyrin with Nucleobases.

Supramolecular self-assembly of an octaphosphonate tetraphenyl porphyrin with three different nucleobases (adenine, cytosine, and thymine) was studied. Porphyrin 1 with 8 and 10 equiv of cytosine produces light-harvesting ring-like structures, that is, architectures similar to those observed in natural light-harvesting antenna. However, porphyrin assembled with adenine or thymine resulted in prisms and microrods, respectively. UV-vis absorption, fluorescence, and dynamic light scattering were used to determine the mode of aggregation in solution. Scanning electron microscopy and X-ray diffraction spectroscopy used to visualize the self-assembled nanostructures and their behavior in the solid state, respectively. Thus, we believe that this study may demonstrate a deeper understanding on how one needs to manipulate donor/acceptor subunits in supramolecular assemblies to construct artificial antenna architectures.

Light triggered encapsulation and release of C60 with a photoswitchable TPE-based supramolecular tweezers.

Stimuli responsive hosts for C60 can control its binding and release on demand. A photoswitchable TPE based supramolecular host can encapsulate C60 in the Z-form with a markedly different visual change in the colour. In addition, the Z-1 bound C60 has been characterized by various spectroscopic methods and mass spectrometry. Upon exposure to visible light (>490 nm), the host switches to the E-form where the structural complementarity with the guest is destroyed as a result of which the C60 is disassembled from the host. The results described herein reveals an actionable roadmap to pursue further advances in component self-assembly particularly light-induced association and dissociation of a guest molecule.

Meet the Board of ChemistryOpen: Sheshanath†V. Bhosale.

Sheshanath V. Bhoslae received his PhD from Freie University Berlin (Germany) in supramolecular chemistry under the supervision of Prof. J. H. Fuhrhop in 2004. He then pursued his postdoctoral studies with Prof. S. Matile at University of Geneva (Switzerland) under the auspices of a Roche Foundation Fellowship. This was followed by a stay at Monash University (Australia) for 5 years as an ARC-APD Fellow. He worked at RMIT University, Melbourne (Australia) for 6 years as ARC-Future Fellowship. Currently, Prof. Bhosale is working at the Department of Chemistry, Goa University (India) as a UGC-FRP Professor, His research interests lie in the design and synthesis of π-functional materials, especially small molecules, for sensing, biomaterials, and supramolecular chemistry applications. So far, Prof. Bhosale has produced 185 research articles and his work has been cited more than 4400 times, giving him an h-index of 32. He currently serves as an active Editorial Board member for ChemistryOpen.