Chitin, as a fundamental polysaccharide in invertebrate skeletons, continues to be actively investigated, especially with respect to new sources and the development of effective methods for its extraction. Recent attention has been focused on marine crustaceans and sponges; however, the potential of spiders (order Araneae) as an alternative source of tubular chitin has been overlooked. In this work, we focused our attention on chitin from up to 12 cm-large Theraphosidae spiders, popularly known as tarantulas or bird-eating spiders. These organisms “lose” large quantities of cuticles during their molting cycle. Here, we present for the first time a highly effective method for the isolation of chitin from Caribena versicolor spider molt cuticle, as well as its identification and characterization using modern analytical methods. We suggest that the tube-like molt cuticle of this spider can serve as a naturally prefabricated and renewable source of tubular chitin with high potential for application in technology and biomedicine.

Spongin is a fundamental biopolymer that has played a crucial role in the skeletogenesis of keratosan sponges for over 800 million years. This biomaterial had so far remained chemically unidentified and believed to be an enigmatic type of halogenated collagen-keratin-based bioelastomer. Here we show collagen I and III as the main structural components of spongin. Proteomics, ¹³C solid state NMR and Raman spectroscopy confirm the identity of collagenous domains in spongin with collagen from mammals. Using an HPLC-MS analysis, we found halogenated di- and tri-tyrosines as crosslinking agents in spongin. Using molecular dynamics modeling, we solvated the crystal structures of collagen mimetic peptides for type I and type III collagens in four different systems, including selected brominated crosslinks. The results underscore the complex interplay between the collagen structures and crosslinks, raising intriguing questions about the molecular mechanisms underlying collagen chemistry within spongin as an ancient biocomposite.

Al‐ion batteries employing natural graphite cathodes have been proposed as a valid alternative to Li‐ion systems due to their low‐cost and sustainability, as well as a stable long‐term cycle life. In contrast to commonly used but typically expensive ionic‐liquid‐based electrolytes, our reported Al‐graphite batteries use AlCl₃/urea and AlCl₃/acetamide deep eutectic solvents (DES, also known as ionic liquid analogues) as low‐cost alternative. By carefully selecting amide composition, Al speciation in the DES electrolyte can be modified, as confirmed by Raman, NMR and IR spectroscopy. We correlate the speciation changes to resulting battery performance by systematic electrochemical investigations of Al‐graphite batteries employing urea and acetamide eutectics of different compositions. The practical applicability was demonstrated using long‐term cycling experiments with >8000 cycles, exhibiting a specific capacity of around 50 mAh/g at a current rate of 2 A/g.

Proceeding our initial studies of compounds with formally dative TM→Si bonds (TM = Ni, Pd, Pt), which feature a paddlewheel arrangement of four (N,S) or (N,N) bridging ligands around the TM–Si axis, the current study shows that the (N,O)-bidentate ligand 2-pyridyloxy (pyO) is also capable of bridging systems with TM→Si bonds (shown for TM = Pd, Cu). Reactions of MeSi(pyO)₃ with [PdCl₂(NCMe)₂] and CuCl afforded the compounds MeSi(µ-pyO)₄PdCl (1) and MeSi(µ-pyO)₃CuCl (2), respectively. In the latter case, some crystals of the Cu(II) compound MeSi(µ-pyO)₄CuCl (3) were obtained as a byproduct. Analogous reactions of Si(pyO)₄, in the presence of HpyO, with [PdCl₂(NCMe)₂] and CuCl₂, afforded the compounds [(HpyO)Si(µ-pyO)₄PdCl]Cl (4), (HpyO)₂Si[(µ-pyO)₂PdCl₂]₂ (5), and (HpyO)₂Si[(µ-pyO)₂CuCl₂]₂ (6), respectively. Compounds 1–6 and the starting silanes MeSi(pyO)₃ and Si(pyO)₄ were characterized by single-crystal X-ray diffraction analyses and, with exception of the paramagnetic compounds 3 and 6, with NMR spectroscopy. Compound 2 features a pentacoordinate Si atom, the Si atoms of the other complexes are hexacoordinate. Whereas compounds 1–4 feature a TM→Si bond each, the Si atoms of compounds 5 and 6 are situated in an O₆ coordination sphere, while the TMCl₂ groups are coordinated to pyridine moieties in the periphery of the molecule. The TM–Si interatomic distances in compounds 1–4 are close to the sum of the covalent radii (1 and 4) or at least significantly shorter than the sum of the van-der-Waals radii (2 and 3). The latter indicates a noticeably weaker interaction for TM = Cu. For the series 1, 2, and 3, all of which feature the Me–Si motif trans-disposed to the TM→Si bond, the dependence of the TM→Si interaction on the nature of TM (Pd(II), Cu(I), and Cu(II)) was analyzed using quantum chemical calculations, that is, the natural localized molecular orbitals (NLMO) analyses, the non-covalent interaction (NCI) descriptor, Wiberg bond order (WBO), and topological characteristics of the bond critical points using the atoms in molecules (AIM) approach.