An updated review on boron removal from water through adsorption processes

Boron is an essential micronutrient that has raised much interest, given the narrow balance between its necessity and toxicity. Both natural and anthropogenic emissions of boron into water sources can eventually deteriorate water quality and endanger the ecosystem. In this review, we first present a general outline of the importance of boron, boron chemistry in water, boron contamination, and its consequences followed by the recent progress in boron removal methods based on adsorption. The adsorbents for deboronation can generally be classified based on the functional groups present; chelating groups, metal oxides, and layered double hydroxides. To comprehensively address these adsorption methods, a detailed discussion on the reaction mechanism of each system is done followed by a summary of the progress in the field during the past 5 years. Finally, some characterization techniques used in deboronation studies and suggestions for future research and applications together with possible improvements to the existing systems are presented. Graphical abstract

Tribute to Josef Michl

It is our great pleasure to introduce the Festschrift of Chemistry to honor professor Josef Michl (Figure 1) on the occasion of his 80th birthday and to recognize his exceptional contributions to the fields of organic photochemistry, quantum chemistry, biradicals and biradicaloids, electronic and vibrational spectroscopy, magnetic circular dichroism, silicon and boron chemistry, supramolecular chemistry, singlet fission, and molecular machines [...]

Boron proxies and biomineralisation: the possible, the impossible and the likely.

<p>The abundance and isotopic content of boron in carbonate biominerals provide our best records of ocean carbon chemistry and pH, which have proved instrumental in studying past episodes of CO<sub>2</sub>-induced climate change. The boron proxies are based on the theory that carbonates solely incorporate B(OH)<sub>4</sub><sup>-</sup> in proportion to seawater B(OH)<sub>4</sub><sup>-</sup>/HCO<sub>3</sub><sup>-</sup> or B(OH)<sub>4</sub><sup>-</sup>/CO<sub>3</sub><sup>2-</sup>, capturing both the state of the ocean C system and the pH-dependent isotopic composition of B(OH)4-. However, models of biomineral<span>is</span>ation invoke significant modification of internal carbon chemistry to facilitate calcification, and substantial proton export has been observed during carbonate formation. The pH, carbon and boron chemistry at the site of calcification cannot be the same as that of external seawater. How, then, do biominerals appear to record seawater B(OH)<sub>4</sub><sup>-</sup>? While unanswered, this question raises serious problems for our interpretation and use of the B proxies.</p><p>We explore this question using a quantitative model of B transport and incorporation in biomineral<span>is</span>ation. Three key fluxes dominate biomineral formation: CaCO<sub>3</sub> precipitation, the exchange of seawater with the external environment, and ion transport across membranes by diffusion or active pumping. By reducing the problem to the balance between these three key fluxes, it is possible to explore a wide range of biominera<span>lis</span>ation scenarios with minimally restrictive assumptions. Within this framework, we consider both the transport of B(OH)<sub>4</sub><sup>-</sup>, and the transport and passive diffusion of membrane-permeable B(OH)<sub>3</sub>, allowing us to explore a comprehensive range of candidate biomineral<span>is</span>ation scenarios and B transport processes.</p><p>By explicitly including the independent transport of both B species, our model offers two key insights into the mechanisms behind the boron proxies and biomineral<span>is</span>ation:</p><ol><li> <p>We identify biomineralisation mechanisms that allow B geochemistry to record external seawater conditions, despite the modified chemistry at the calcification site.</p> </li> <li> <p>We constrain the dynamics of the calcification environment (e.g. ‘closed’ vs. ‘open’ or Rayleigh- vs. transport-dominated system) by inverting the model to consider paired B/Ca and δ<sup>11</sup>B data, offering key new constraints on ion transport processes in biomineral<span>is</span>ation.</p> </li> </ol>

Recent Advances in Metal-Catalyzed Alkyl–Boron (C(sp3)–C(sp2)) Suzuki-Miyaura Cross-Couplings

Boron chemistry has evolved to become one of the most diverse and applied fields in organic synthesis and catalysis. Various valuable reactions such as hydroborylations and Suzuki–Miyaura cross-couplings (SMCs) are now considered as indispensable methods in the synthetic toolbox of researchers in academia and industry. The development of novel sterically- and electronically-demanding C(sp3)–Boron reagents and their subsequent metal-catalyzed cross-couplings attracts strong attention and serves in turn to expedite the wheel of innovative applications of otherwise challenging organic adducts in different fields. This review describes the significant progress in the utilization of classical and novel C(sp3)–B reagents (9-BBN and 9-MeO-9-BBN, trifluoroboronates, alkylboranes, alkylboronic acids, MIDA, etc.) as coupling partners in challenging metal-catalyzed C(sp3)–C(sp2) cross-coupling reactions, such as B-alkyl SMCs after 2001.