Mass spectrometry for multi-dimensional characterization of natural and synthetic materials at the nanoscale

Characterization of materials at the nanoscale plays a crucial role in in-depth understanding the nature and processes of the substances. Mass spectrometry (MS) has characterization capabilities for nanomaterials (NMs) and nanostructures by offering reliable multi-dimensional information consisting of accurate mass, isotopic, and molecular structural information. In the last decade, MS has emerged as a powerful nano-characterization technique. This review comprehensively summarizes the capabilities of MS in various aspects of nano-characterization that greatly enrich the toolbox of nano research. Compared with other characterization techniques, MS has unique capabilities for real-time monitoring and tracking reaction intermediates and by-products. Moreover, MS has shown application potential in some novel aspects, such as MS imaging of the biodistribution and fate of NMs in animals and humans, stable isotopic tracing of NMs, and risk assessment of NMs, which deserve update and integration into the current knowledge framework of nano-characterization.

Light-Controlled Regioselective Synthesis of Fullerene Bis-Adducts

Multi-functionalization and isomer-purity of fullerenes are crucial tasks for the development of their chemistry in various fields. In both current main approaches-tether-directed covalent functionalization and supramolecular masks-the control of regioselectivity requires multi-step synthetic procedures to prepare the desired tether or mask. Herein, we describe light-responsive tethers, containing an azobenzene photoswitch and two malonate groups, in the double cyclopropanation of [60]fullerene. The formation of the bis-adducts and their spectroscopic and photochemical properties, as well as the effect of azobenzene photoswitching on the regiochemistry of the bis-addition, have been studied. The behavior of the tethers depends on the geometry of the connection between the photoactive core and the malonate moieties. One tether lead to a strikingly different adduct distribution for the E and Z isomers, indicating that the covalent bis-functionalization of C₆₀ can be controlled by light.

A quantum study on novel azo-dyes containing a fullerene C60 unit as a smart material for optoelectronic applications

Quantum chemical calculations of some novel azo-dyes containing a fullerene C60 unit as a smart material have been carried out with the aims to determine their cis and trans electronic properties and to describe the change of their quantum parameters as a result of the trans/cis isomerization of these molecules. The effects of electron-withdrawing or electron-releasing groups on the R-position of these molecules on electronic, optical, spectroscopic, and other properties of these molecules have been considered with DFT and TDDFT calculations. The obtained results of the calculations show that compounds "b" and "c" with the strongest electron-releasing groups in the R-position of these molecules, particularly the trans isomers of these compounds, with higher chemical softness, higher electrophilicity index, higher thermodynamic properties, and higher charge transfer values, have the better electronic and optical properties and therefore the better chemical reactivity compared to the other compounds. Graphical abstract.

Fine-Tuning the Electronic Properties of Azo Chromophore-Incorporated Perylene Bisimide Dyads

Perylene bisimide (PBI) and azo-compounds are fascinating molecules with interesting optical properties. Here, we combine the two chromophores to prepare nonconjugated and conjugated stable azo-PBI dyes. The detailed structural characterization, comparison of properties, and solid-state self-assembly of the compounds are discussed. The incorporation of azo groups at the bay side of PBI led to significant changes in optical properties as compared to the model PBIs (M₁ and M₂). All new azo-PBIs showed photoinduced isomerization, which caused disaggregation and enhancement in fluorescence. The amine-incorporated azo-PBIs (3 and 6) reduced chloroauric acid into gold nanoparticles. The current study offers a simple synthetic strategy and comparison of the properties of conjugated and nonconjugated azo-PBIs, which could be useful in photoelectronic devices.