Alessandro Bismuto

Lanthanide‐based bioimaging has attracted tremendous attention in biomedical research. Herein, recent advances in the design of multipurpose upconversion, downshifting, lifetime, photoacoustic and multimodal lanthanide‐imaging nanoprobes (LINPs), as well as their representative activatable, multiplexing or multimodal biophotonic applications are summarized in detail.

Abstract

Optical imaging plays a growing role in modern biomedical research and clinical applications due to its high sensitivity, superb spatiotemporal resolution and minimal hazards. Lanthanide‐doped nanoparticles (LDNPs), as a classical category of luminescent materials, exhibit promising photostability, near‐infrared (NIR)‐excited frequency up‐/down‐converting capabilities, emission fine‐tuning and multispectral features, which have greatly promoted the endeavors of deeper and clearer diagnostics in complex living conditions. This review focuses on the recent advances of LDNP‐based multipurpose imaging studies using upconversion, downshifting, lifetime, photoacoustic and multimodal nanoprobes in the NIR (650–1000 nm) and the second near‐infrared window (NIR‐II, 1000–1700 nm). The principle and design of various functional, activatable, multiplexing or multimodal lanthanide‐imaging nanoprobes (LINPs) as well as representative biophotonic applications are summarized in detail. In addition, the future perspectives and challenges for facilitating LINPs to clinical translations are discussed.

Far and NIR: A “turn‐on” near‐infrared (NIR) fluorescent probe, PZ‐N, for the selective detection of copper (II) ions (Cu²⁺) has been developed. The probe PZ‐N showed quick response and high sensitivity towards Cu²⁺. Moreover, the probe PZ‐N was also capable of detecting Cu²⁺ in living cells.

Abstract

Abstract: It is well known that copper ions play a critical role in various physiological processes. However, a variety of human diseases are tightly correlated with copper overload. Although there are numerous fluorescent probes capable of detecting copper ions, most of them are “turn‐off” probes owing to copper (II) ions fluorescence quenching effect, resulting in poor sensitivity. Herein, a novel “turn‐on” near‐infrared (NIR) fluorescent probe PZ‐N based on phenoxazine was designed and synthesized for the selective detection of copper (II) ions (Cu²⁺). Upon the addition of Cu²⁺, the probe could quickly react with Cu²⁺ and emit strong fluorescence, along with colour change from colourless to obvious blue. Moreover, the probe PZ‐N showed good water solubility, high selectivity, and excellent sensitivity with low limit of detection (1.93 nM) towards copper (II) ions. More importantly, PZ‐N was capable of effectively detecting Cu²⁺ in living cells.

Sentenced to live: Continuous development of synthetic strategies for the generation and stabilization of frequently transient main‐group species has led to the isolation of several long‐lived radicals of the heavy group 15 elements during the last decade. In this minireview, a comprehensive overview of the synthesis and properties of As‐, Sb‐, and Bi‐centered radicals is provided.

The syntheses and properties of long‐lived arsenic, antimony, and bismuth‐centered radicals are reviewed. In contrast to the rich phosphorus‐based radical chemistry, that of the heavier congeners is far less advanced, which can be attributed to the increased instability of coordinatively and electronically unsaturated heavy main‐group element centers. However, the development of new synthetic strategies and stabilization methods particularly in the last decade enabled the isolation and characterization of several unpaired electron‐containing heavy group 15 element species featuring various structural motifs and electronic properties. The long‐lived character of these radicals allowed for the elucidation of their electronic structures and bonding properties, as well as the exploration of their unique reactivity.

The reactions of boron trichloride with diiminopyridine ligands featuring 2,6‐diisopropylphenyl groups on the nitrogen atoms and varying groups on the α‐carbon (H, CH₃, and Ph) were investigated. N,N'‐chelated cationic BCl₂ complexes with BCl₄ ^– counteranions were isolated with the hydrogen and phenyl‐substituted ligands, while a mixture was obtained for the methyl variant.

The reactions of boron trichloride with diiminopyridine ligands featuring 2,6‐diisopropylphenyl groups on the imine nitrogen atoms and varying groups on the α‐carbon atoms (H, CH₃, and Ph) were investigated. N,N'‐chelated cationic BCl₂ complexes with BCl₄ ^– counteranions were isolated with the hydrogen and phenyl‐substituted ligands while a mixture was obtained for the methyl variant.

Py‐IPH, a pyrene‐based fluorogen with good thermal and mechanical stability was simply prepared by the Schiff base reaction and applied in the detection of antimony. Py‐IPH presented special excimer fluorescence in the mixture of THF and water with 80 % of water, and exhibited perfect fluorescent response to antimony. The mechanism was demonstrated to be the increasing speed of the formation of pyrene excimers in the system owing to the coordination between antimony and IPH group in Py‐IPH. Moreover, based on the special interaction between Py‐IPH and antimony, it could distinguish antimony with other cations well with high specificity and selectivity.

An improved route to d‐block and main group NSO complexes is presented including the synthesis of the first antimony(V) complexes, (Ar₃Sb(NSO)₂), and copper examples [CuBipy(PPh₃)NSO]. The structures of eight complexes are reported. The observed variation in M–N–S bond angles is due to the combination of orbital overlap (ligand‐to‐metal bonding) and the degree of ionicity of the bonding.

A new series of 2,4,6‐triaryl‐λ⁵‐phosphinines were synthesized and characterized. Supported by DFT calculations, the structure–property relationships of these unsaturated phosphorus heterocycles were investigated in detail. For the first time, an organic light‐emitting device was developed based on a blue phosphinine emitter.

Abstract

A new series of 2,4,6‐triaryl‐λ⁵‐phosphinines have been synthesized that contain different substituents both on the carbon backbone and the phosphorus atom of the six‐membered heterocycle. Their optical and redox properties were studied in detail, supported by in‐depth theoretical calculations. The modularity of the synthetic strategy allowed the establishment of structure–property relationships for this class of compounds and an OLED based on a blue phosphinine emitter could be developed for the first time.

Copper‐catalyzed borylative multicomponent couplings, involving olefins and C−N electrophiles, constitute an efficient approach to high‐value amine and nitrile products. This Minireview assesses the progress in this rapidly emerging field and surveys the borylative union of allenes, dienes, styrenes, and related olefins, with imines, nitriles, and related electrophiles.

Abstract

Copper‐catalyzed borylative multicomponent reactions (MCRs) involving olefins and C−N electrophiles are a powerful tool to rapidly build up molecular complexity. The products from these reactions contain multiple functionalities, such as amino, cyano and boronate groups, that are ubiquitous in medicinal and process chemistry programs. Copper‐catalyzed MCRs are particularly attractive because they use a relatively abundant and non‐toxic catalyst to selectively deliver high‐value products from simple feedstocks such as olefins. In this Minireview, we explore this rapidly emerging field and survey the borylative union of allenes, dienes, styrenes and other olefins, with imines, nitriles and related C−N electrophiles.

A novel tetranuclear iron dicationic complex has been synthesized and isolated as a hexafluorophosphate salt. The dicationic moiety constitutes a structured charge container able to encode binary information in the charge configuration. It constitutes a QCA cell. The IR data are characteristic of a class II mixed‐valence complex, while the physical properties are consistent with a localization of the positive charges on the antipodal positions to minimize coulomb repulsion and favor antiferromagnetic exchange coupling.

Abstract

The unprecedented tetrairon dication [{Cp*(dppe)FeC≡C‐}₄‐μ‐(1,2,4,5‐C₆H₂)](PF₆)₂ (1 ) was obtained through a sequence of three reactions from 1,2,4,5‐tetraethynylbenzene, Cp*(dppe)FeCl (Cp*=C₅Me₅, dppe=1,2‐bis(diphenylphosphino)‐ethane), KOt Bu, and ferrocenium hexafluorophosphate. The cyclic voltammogram of the target molecule, isolated in 77 % yield, exhibits four well separated and reversible redox events showing that 1 is thermodynamically stable with respect to disproportionation (K c>10⁶). The tetranuclear dication 1 was characterized by XRD on single crystal, IR and NMR spectroscopies and Mössbauer spectrometry. The experimental data show that 1 behaves as a class II mixed‐valence complex with the positive charges preferentially disposed on antipodal positions. This new molecule can be regarded as a potential molecular prototype of quantum dot cellular automata.

Barium rocks ! A new carbazole‐based ligand, which is readily available on large scale, enables the syntheses of yet unknown solution‐stable barium complexes, for example, barium fluoride and barium stannylide species, which display unusual bonding patterns.

Abstract

Reported here is a readily available bis(imino)carbazole‐based proligand that constitutes a convenient entry point into the challenging synthetic molecular chemistry of barium. It enables the preparation of rare or even, up to now, unknown, solution‐stable heteroleptic barium complexes. The syntheses and structural features for the first molecular barium fluoride and the first barium stannylide, with an unsupported Ba−Sn bond, are described, along with other carbazolate barium species: an amide (both a remarkably stable starting material and an excellent hydrophosphination precatalyst), iodide, and silanylide. DFT analysis of bonding patterns in the barium stannylide and barium silanylide highlights a prevailingly ionic barium–tetrelide bond with a small covalent contribution.

The MNO segment should be linear for NO ⁺ but bent for NO ⁻ . Though this statement is taken from a IUPAC publication on oxidation states (OS), it mirrors a common belief. However, deriving the OS by the effective‐oxidation‐state procedure (EOS), the new nitrosylcobalt species (see the Figure) resembled a Co^I(NO⁺) couple instead of the expected Co^III(NO⁻).

Abstract

Nitrosyl–metal bonding relies on the two interactions between the pair of N–O‐π* and two of the metal's d orbitals. These (back)bonds are largely covalent, which makes their allocation in the course of an oxidation‐state determination ambiguous. However, apart from M‐N‐O‐angle or net‐charge considerations, IUPAC′s “ionic approximation” is a useful tool to reliably classify nitrosyl metal complexes in an orbital‐centered approach.

The light fantastic : A highly effective C−O coupling reaction of (hetero)aryl electrophiles with primary and secondary alcohols is reported. Catalyzed by a Ni^II‐aryl complex under long‐wave UV irradiation in the presence of a soluble amine base without any additional photosensitizer, the reaction enables the etherification of aryl bromides and aryl chlorides as well as sulfonates with a wide range of primary and secondary aliphatic alcohols.

Abstract

A highly effective C−O coupling reaction of (hetero)aryl electrophiles with primary and secondary alcohols is reported. Catalyzed by a Ni^II‐aryl complex under long‐wave UV (390–395 nm) irradiation in the presence of a soluble amine base without any additional photosensitizer, the reaction enables the etherification of aryl bromides and aryl chlorides as well as sulfonates with a wide range of primary and secondary aliphatic alcohols, affording synthetically important ethers. Intramolecular C−O coupling is also possible. The reaction appears to proceed via a Ni^I–Ni^III catalytic cycle.

The Pudovik reaction is an atom‐economic addition of phosphane oxides across alkynes, strongly depending on the nature of the s‐block metal, the solvent, the bulkiness of P‐bound groups, and the concentration. Bulky mesityl groups can interact with the newly formed C=C bond of the alkenylphosphane oxides.

Abstract

The hydrophosphorylation of phenylacetylene with di(aryl)phosphane oxides Ar₂P(O)H (Pudovik reaction) yields E /Z ‐isomer mixtures of phenylethenyl‐di(aryl)phosphane oxides (1 ). Alkali and alkaline‐earth metal di(aryl)phosphinites have been studied as catalysts for this reaction with increasing activity for the heavier s‐block metals. The Pudovik reaction can only be mediated for di(aryl)phosphane oxides whereas P‐bound alkyl and alcoholate substituents impede the P−H addition across alkynes. The demanding mesityl group favors the single‐hydrophosphorylated products 1‐Ar whereas smaller aryl substituents lead to the double‐hydrophosphorylated products 2‐Ar . Polar solvents are beneficial for an effective addition. Increasing concentration of the reactants and the catalyst accelerates the Pudovik reaction. Whereas Mes₂P(O)H does not form the bis‐phosphorylated product 2‐Mes , activation of an ortho ‐methyl group and cyclization occurs yielding 2‐benzyl‐1‐mesityl‐5,7‐dimethyl‐2,3‐dihydrophosphindole 1‐oxide (3 ).