Charge density wave (CDW) phases are unconventional quantum states that often arise in low-dimensional metallic systems and are themselves found alongside other exotic phenomena. Finding such states in porous materials is exceedingly rare. In fact, [Ln(NO 3 ) 1-x ] 3 (HOTP) 2 (Ln = La, Nd; H 6 HOTP = 2,3,6,7,10,11- hexahydroxytriphenylene; LnHOTP ) is the only example of a porous material wherein a CDW state has been proposed on the basis of a structural modulation. However, whether the modulation is trivial, and thus purely structural in nature, or it stems from a CDW, and thus has electronic origin, remains unknown. Here, low-temperature and high-pressure crystallography provide evidence for an electronic origin of the CDW phase in a series of LnHOTP (Ln = La, Ce, Pr, Nd, and Sm) MOFs, including the original La and Nd materials. We show that the modulation affects the relative rotation of neighboring HOTP ligands, and that the magnitude of the wavevector that defines the modulation, q , is sensitive to pressure. Importantly, the wavevector exhibits commensurability lock-in at one third of the c unit cell parameter, q = 1/3 c , providing key evidence for energetic stabilization of the CDW phase.

Charge density wave (CDW) phases are unconventional quantum states that often arise in low-dimensional metallic systems and are themselves found alongside other exotic phenomena. Finding such states in porous materials is exceedingly rare. In fact, [Ln(NO3)1-x ]3(HOTP)2 (Ln = La, Nd; H6HOTP = 2,3,6,7,10,11-hexahydroxytriphenylene; LnHOTP) is the only example of a porous material wherein a CDW state has been proposed on the basis of a structural modulation. However, whether the modulation is trivial, and thus purely structural in nature, or it stems from a CDW, and thus has electronic origin, remains unknown. Here, low-temperature and high-pressure crystallography provide evidence for an electronic origin of the CDW phase in a series of LnHOTP (Ln = La, Ce, Pr, Nd, and Sm) MOFs, including the original La and Nd materials. We show that the modulation affects the relative rotation of neighboring HOTP ligands, and that the magnitude of the wavevector that defines the modulation, q, is sensitive to pressure. Importantly, the wavevector exhibits commensurability lock-in at one-third of the c unit cell parameter, q = 1/3 c, providing key evidence for energetic stabilization of the CDW phase.

Indenofluorenes have become an important class of polycyclic aromatic hydrocarbons that are of interest for their nonalternant structures and intriguing properties. In this report, we unveil the reversible redox behavior of doubly boron-doped indenofluorenes (DBIFs). The diboraindeno[2,1-b]fluorene isomer is disclosed for the first time, where reduction of 18 π-electron DBIFs yield new 19 π-electron radical anions and 20 π-electron dianions. Notably, the DB[2,1-b]IF radical anion is the first isolated and structurally characterized 19 π-electron indenofluorene derivative, displaying ultra low-energy absorption in the near-infrared (NIR)-IIb region (1594 nm, tailing to 1850 nm). In addition, the synthesis of three 20 π-electron DBIFs highlight isomer-dependent electronic structure modulation. While the para-quinodimethane (QDM) DB[1,2-b]IF is NMR-active and has a singlet ground state (NIR emissive, 900 nm), the meta-QDM DB[2,1-b]IF compounds are EPR-active and have a triplet ground state (NIR absorption out to 1350 nm), both of which are isoelectronic with their respective pure-hydrocarbon indenofluorene analogs. Initial reactivity studies of the reduced compounds were conducted, which reveal that the two boron centers react cooperatively to afford unusual macrocyclic products. These results highlight reduced, aryl-substituted DBIFs as true electronic mimics for carbonaceous indenofluorenes, with expanded redox capabilities, optical properties, and chemical reactivities that result from boron-doping.

Metal-organic frameworks (MOFs) assembled from achiral building blocks that nonetheless crystallize in Sohncke space groups represent an underexplored route to chiral porous materials. However, accessing such materials requires enantioselective crystallization strategies, which remain a fundamental challenge. Here, we employ a chiral induction approach to produce enantiomorphically enriched CFA-1 (Zn5(OAc)4(bibta)3; H2bibta = 1H,1’H-5,5’bibenzo[d][1,2,3]triazole), a MOF constructed from achiral linker that crystallizes in the P321 chiral space group. Using scanning electron microscopy (SEM) and 3D electron diffraction (3DED) for absolute structure determination, we establish that (R)-ibuprofen induces a left-handed (M) crystal morphology alongside a right-handed (P) absolute crystal structure, designated P-CFA-1, while (S)-ibuprofen affords the opposite enantiomorph. Enantiomorphically enriched CFA-1 promotes catalytic asymmetric transformations, highlighting the potential of intrinsically chiral frameworks for asymmetric catalysis.

Steroid hormones are central regulators of eukaryotic physiology, yet their signaling pathways are also exploited as key targets in cross-kingdom endocrine interference. Among them, cardenolides are steroid hormones in mammals that target sodium-potassium adenosine triphosphatase (Na+/K+-ATPase) to modulate ionic homeostasis. Notably, at least 17 plant orders are known to produce cardenolides as potent antiherbivore defenses by mimicking this signaling axis. A prominent example is digoxin, an FDA-approved cardiac drug sourced from foxglove. Despite decades of study, the biochemical basis by which plants evolved this endocrine mimicry remains unclear. Here, we identify S14βH, a noncanonical 2-oxoglutarate/Fe(II)-dependent dioxygenase (2OGD) that catalyzes stereoinverted steroid C14β-hydroxylation through an unprecedented mechanism involving hydrogen atom transfer, substrate reorientation, and opposite-face hydroxyl rebound. An intricate metabolic network comprising enzymatic redox transformations and malonylation, together with spontaneous lactonization, then channels 14β-hydroxylated pregnenolone toward the core cardenolide digitoxigenin. Comparative biochemical and evolutionary analyses further reveal that mammalian-like steroidogenesis is conserved in seed plants and has been independently co-opted for cardenolide biosynthesis across diverse lineages. Our findings expand the mechanistic scope of radical enzymology, illustrate how the malleability of plant metabolism enables repeated endocrine mimicry, and ultimately motivate future investigation into potential hormonal functions of steroids produced via mammalian-like steroidogenesis in plants.

2D materials exhibiting in-plane anisotropy enable novel functionality in electronic, optoelectronic, and photonic devices, yet their availability is generally limited to naturally-occurring low-symmetry van der Waals compounds. Here, we demonstrate an approach to structural engineering in a family of blue-emitting 2D silver phenylchalcogenide semiconductors based on steric interactions among surface-bound organic molecular ligands. By strategically halogenating specific sites of phenyl ligands, we demonstrate dramatic changes to the inorganic AgSe plane in mithrene (silver phenylselenolate, AgSePh). Density functional theory revealed pronounced in-plane electronic anisotropy for direct-gap fluorinated derivatives, while a chlorinated variant exhibited a direct-to-indirect bandgap transition. Furthermore, some fluorinated variants displayed strongly polarized absorption and luminescence, accompanied by a 10x enhancement in photoluminescence quantum yield. This work establishes a versatile approach for tailoring optoelectronic properties in hybrid semiconductors that is difficult or impossible to achieve in all-inorganic materials alone, offering new opportunities in advanced material design.

Cyanogen N-oxide (NCCNO) is one of the simplest molecules containing carbon, nitrogen, and oxygen, making it an attractive interstellar spectroscopic probe and an intriguing building block in prebiotic chemistry. However, detailed studies of NCCNO are hindered by its high reactivity and propensity for autopolymerization. In this report, monomeric, carbene-stabilized cyanogen N-oxide (1) is synthesized by the unusual complete dehydrogenation of C-H-activated acetonitrile via the addition of "superelectrophilic" nitronium (NO2+). Experimental and computational studies of 1 reveal spectroscopic features supporting its characterization as a trapped form of NCCNO, while novel electronic structure properties distinguish it from closely related organic nitrile oxides. Compound 1 also readily coordinates metal ions (Mg2+ and Fe3+), providing evidence that the NCCNO molecule can display preferential reactivity at the O-terminus over the N-terminus but nevertheless is capable of multiple binding modes. The stabilized NCCNO molecules also undergo reduction to isolable cyanogen N-oxide radical anions─compounds featuring radical localization on the O-terminus with minimal carbene involvement, supporting their assignment as open-shell forms of cyanogen N-oxide. Finally, dehydrogenation conditions were applied to other R-CH3 groups in methyl acetate and nitromethane to synthesize additional small nitrile oxides: methyl cyanoformate N-oxide, which is unknown in its free form, and fulminic acid, the simplest organonitrile. Together, these results showcase a versatile strategy for converting stable carbene C-H activation products to isolable forms of highly reactive carbonaceous small molecules.

The first example of a CN σ‐bond activation in tert‐butyl isocyanate and isothiocyanate by a 3,5‐bis(trimethylsilyl)‐phosphinine‐B(C6F5)3 Lewis pair is reported. Despite the inherently low nucleophilicity of phosphinines, the first step of the observed reactions is the unusually facile tert‐butylation of the phosphinine via an SN1 pathway, yielding the unprecedented 1‐tBu‐phosphininium cation. The high reactivity of this intermediate leads to subsequent follow‐up reactions with the excess reactant as well as side‐products, forming additional phosphorus compounds under mild conditions via a complex reaction network. In stark contrast, the reaction of tBuNCO and tBuNCS with a classical frustrated Lewis pair leads to simple decomposition of the iso(thio)cyanate. This work not only reveals a new mode of CN σ‐bond activation in iso(thio)cyanates by compounds based on main‐group elements, but also suggests a direct pathway for the selective P‐functionalization of phosphinines, opening up avenues for the targeted synthesis of such otherwise inaccessible aromatic phosphorus heterocycles.

Noncovalent interactions between aromatic rings can dictate the crystal structures of organic optoelectronic materials. While cofacial interactions of fluorinated and non-fluorinated arenes are useful supramolecular synthons, the impacts of the structural details on these interactions remain unpredictable, particularly with the types of heterocycles common in materials derived from pi-conjugated molecules. In this work, a combination of optical spectroscopy and X-ray crystallography demonstrates that both the degree of fluorination of a benzyl ester side chain and the regiochemical connectivity of a benzothiophene (BT) to an arylene-ethynylene backbone impact whether intramolecular cofacial stacking occurs or not. Surprisingly, the thienothiophene (TT) analog, which has an isoelectronic pi-system with BT while a stronger electron donor when a part of donor-acceptor pi-systems, did not show any evidence of cofacial stacking with fluoroarene side chains, regardless of the extent of fluorination. Quantum-chemical modelling rationalizes the dependence on BT regiochemistry, suggesting that while dispersion interactions comprise the largest individual component of attractive forces in stacking interactions, the strength of electrostatic interactions correlates best with the likelihood of intramolecular stacking interactions occurring in the solids. Finally, many of these molecules show polymorphic behaviour, with examples of blue-shifting and red-shifting mechanofluorochromism. Overall, this work enhances our ability to harness local structural details in deploying non-covalent interactions for designing solid state structures of optoelectronic materials.

The two-proton/two-electron electrochemical reduction of a phosphine oxide with elimination of water as the sole byproduct (P(V)=O + 2H+ + 2e- → P(III) + H2O) is reported. Under electrochemical (constant current electrolysis) conditions, reduction of 5-phenylphospholo[3,2-c:4,5-c']dipyridine P-oxide (1 O ) in the presence of a proton donor gives the corresponding phosphine (1) in up to 90% yield and 95% conversion. Electrokinetic data and simulations are consistent with an E r C i E r C i mechanism, in which an initial one-electron reduction brings about rate-limiting protonation of the phosphoryl bond. A regioisomeric phosphine oxide (9-phenylphospholo[2,3-c:5,4-c']dipyridine P-oxide, 2 O ) shows reversible electron transfer (ET) behavior but does not lead to proton-coupled electron transfer (PCET) P=O reduction. These results introduce the electronic design of π-substituents as a tunable mode by which to access previously challenging proton-coupled reduction of the strong P=O bond.

Colloidal superlattices are widely studied for the collective properties emerging from nanocrystal interactions. This focus has shaped the description of superlattices as ordered aggregates of particles that remain structurally unaffected by self-assembly, and whose value lies mainly in the emergent properties they can express. In direct analogy with structural biology, where protein crystals are not the end goal but rather the starting point of scientific inquiry, we instead propose superlattices as tools to characterize nanocrystals and their environment. Indeed, CsPbBr 3 superlattices display striking similarities with protein crystals, sharing comparable unit cell size, structural complexity, and crystallization dynamics. Like proteins, CsPbBr 3 nanocrystals display a measurable contraction of their atomic structure upon self-assembly, which we attribute to a restriction of vibrational freedom by analogy with well-documented protein crystallization dynamics. Like some proteins, CsPbBr 3 nanocrystals reconcile their orthorhombic structure with the cubic symmetry of the superlattice by adopting different orientations without disrupting structural coherence, a mechanism known as rotational order-disorder. Like proteins, nanocrystals self-assemble by retaining a shell of molecules – the ligands – that preserves a chemical environment similar to solution. Inspired by the molecular dynamics studies on water behavior in protein crystals, we exploit this property and the precise geometric information from X-ray diffraction to simulate the behavior of surface ligands, finding that a significant fraction of these molecules may remain free in the interparticle space, where they form micelles resembling the interstitial water networks found in protein crystals. In a final parallel, we show that single-superlattice X-ray diffraction encodes structural information at both the atomic and nanoparticle scales, which can be extracted by adapting strategies from protein crystallography. Together, this evidence prompts a redefinition of CsPbBr 3 superlattices as hybrid organic-inorganic crystals, and highlights structural biology as a source of ideas for studying nanomaterials and engineering their properties. Following this lead, we anticipate that crystallography on supercrystals – or supercrystallography – will provide atomic-resolution insight into elusive features such as surface structure, ligand binding motifs, and the presence of strain fields across the particle core.

Macromolecular folding underlies function in biological systems, yet analogous compact, globular tertiary structures remain rare in synthetic chemistry. Although shapepersistent foldamers and metal-templated knots have been realized, crystallographically resolved globular architectures arising from intramolecular folding of single nonpeptidic macromolecules are unknown. Here we introduce metal–organic knedels (MOKs): compact single-chain globules formed by intramolecular folding of single synthetic macromolecules around multiple metal centers. Specifically, a uniform 2.6 kDa oligomer bearing eight pyridyl donors and three naphthyl linkers undergoes diastereoselective assembly with two Pd(II) centers to afford a discrete complex, MOK-1, where covalent tethering enforces a unique low-symmetry fold and cavity shape not typically accessible in conventional high-symmetry assemblies, as confirmed by NMR spectroscopy, mass spectrometry and single-crystal X-ray diffraction. These findings define a new class of metal–organic architectures and establish intramolecular folding as a strategy for constructing globular synthetic systems.

We report the first paramagnetic boron tetraradical, comprising four boraphenanthrene-type units with boryl radical centers bridged by a central tetraphenylethene (TPE) linker. With strongly π-accepting and sterically demanding cyclic(alkyl)(amino) carbene ligands (3), spin densities localize on the boron-carbene fragments (92%), consistent with a true boron-centered tetraradical. Magnetic measurements of 3 reveal minimal spin-spin coupling, consistent with four noninteracting S = 1/2 centers. In contrast, weaker π-accepting diamino N-heterocyclic carbene ligands delocalize spin density over the TPE core (88%), yielding a boron-containing hydrocarbon biradical (4). Compound 4 exhibits antiferromagnetic interactions (2J = -118 J·mol-1), supporting an open-shell singlet ground state with a thermally accessible triplet excited state.

Migration of palladium‐bound hydrocarbyl ligands to tricoordinate phosphorus ligand P(N(o‐N(2‐pyridyl)C 6 H 4 ) 2 ) ( L ) is demonstrated across a series of Pd(II) organometallic complexes bearing C sp , C sp 2 , and C sp 3 groups. Treatment of ligand L with cis ‐[(TMEDA)PdI(C 6 H 5 )], cis ‐[(TMEDA)PdBr(CH 2 C 6 H 5 )], [(η 3 ‐C 3 H 5 )PdCl] 2 , and trans ‐[PdBr(C≡C─C 6 H 5 )(PPh 3 ) 2 ], respectively, results in migration of the hydrocarbyl group from Pd to P, yielding isolable (σ 4 ‐P)─Pd palladaphosphoranes: L Allyl •Pd Cl , L Bn •Pd Br , L Ph •Pd I , and L CCPh •Pd Br . The mechanistic pathway of the palladaphosphorane formation was investigated by in situ NMR experiments and DFT calculations, suggesting an α‐migration mechanism. Halide exchange with NaBr or NaI affords the corresponding bromide and iodide congeners without disrupting the palladaphosphorane connectivity. 31 P NMR chemical shifts correlate systematically with the identity and hybridization of the hydrocarbyl group, and electronic structure analyses attribute observed trends to variations in the s/p hybrid compositions of the local P─C bond orbitals. This work establishes an underappreciated facet in the reactivity landscape of Pd complexes bearing tricoordinate phosphorus (σ 3 ─P) ligands by demonstrating their ability to undergo nonspectator metal‐to‐ligand group transfer, with implications for designing bifunctional ligand architectures capable of cooperative catalysis.

Correction for ‘Influence of shape on crystal structure and optical properties of heterocyclic conjugated molecules’ by Elisa Guzmán et al. , J. Mater. Chem. C , 2025, 13 , 954–962, https://doi.org/10.1039/D4TC03509G.

The increased mechanical flexibility, solution processability, ease of fabrication, and high Verdet constants have made organic Faraday rotators a promising alternative to conventional inorganic magneto-optical (MO) materials. Despite this, organic Faraday rotators have not been developed to address near-infrared (NIR) MO applications, limiting their device applications. Here, we describe a three-step synthesis and MO characterization of a fused octapyrrolyl cyclooctatetraene (FOPCOT) which exhibits a record high Verdet constant of a small molecule in the NIR-II region. Notably, the cyclooctatetraene core is constructed in a three-step one-pot reaction whereby a N,N'-dipyrrolyl acetylene is generated and immediately reacted with Rosenthal's complex to produce the corresponding zirconacycle intermediate in situ. The cascade is completed with a copper-mediated transmetalation that reductively eliminates to yield the octapyrrolyl cyclooctatetraene. This transformation offers a distinct alternative to conventional methods for pyrrole incorporation into polycyclic aromatic hydrocarbons. Stoichiometric oxidation with AgPF6 affords the oxidized analogues FOPCOT•+ and FOPCOT2+, which display strong optical absorptions at 1743 and 1198 nm, respectively. Magnetic circular dichroism study on spin-coated thin films of FOPCOT2+ yielded a maximum Verdet constant of -2.5 × 105 deg T-1 m-1 at 1224 nm.

Hybrid organic-inorganic semiconductors present new opportunities for optoelectronic materials design not available in all-organic or all-inorganic materials. One example is silver phenylselenide (AgSePh) - or "mithrene" - a blue-emitting 2D organic-inorganic semiconductor exhibiting strong optical and electronic anisotropy. Here, we show that the bandgap of mithrene can be systematically tuned by introducing electron-donating and electron-withdrawing groups to the phenyl ligands. We synthesized nine mithrene variants, eight of which formed 2D van der Waals crystals analogous to those of AgSePh. Density functional theory calculations reveal that these 2D mithrene variants are direct-gap or nearly direct gap semiconductors. Furthermore, we identify correlations between the optical gap and three experimental observables - the Hammett constant, 77Se chemical shift, and selenium partial charge - offering predictive power for bandgap tuning. These findings highlight new opportunities for applying the tools of chemical synthesis to semiconductor materials design.

We report the discovery and comprehensive characterization of the octahydrate phase of magnesium pyrophosphate, Mg2P2O7·8H2O, synthesized via aqueous reactive crystallization of magnesium chloride and sodium pyrophosphate in Tris buffer at pH 8. While Mg2P2O7·3.5H2O and Mg2P2O7·6H2O readily form under these conditions, the octahydrate appears only rarely. However, once nucleated, it can be seeded to reproducibly promote its formation and suppress other hydrate phases. The structure was elucidated using a single crystal and further characterized by powder X-ray diffraction, vibrational spectroscopy, and thermal analysis focused on dehydration behavior. Microscopy techniques (optical, SEM, TEM, and Raman microspectroscopy) revealed a pure phase exhibiting a radiating bladed crystal habit. Unlike other known hydrates, which form nanosheet-like crystals, the octahydrate phase instead grows as large, multidirectional micron-sized crystals. Its markedly faster growth rate and distinct morphology suggest that it is a promising candidate as a pyrophosphate scavenger in in vitro transcription reactions.

Although two-dimensional (2D) electrically conducting metal-organic frameworks (cMOFs) have become prominent due to their numerous potential applications, their structures are often implied or assumed from rather crude powder X-ray diffraction data. Indeed, exceedingly few examples exist of atomic-level structural details coming from single crystal diffraction experiments. Most widely studied among cMOFs are materials based on triphenylene ligands, in particular M3(HOTP)2 (M = Cu, Zn) and [M3(HOTP)2][M3(HOTP)]2 (M = Mg, Ni, Co; H6HOTP = 2,3,6,7,10,11-hexahydroxytriphenylene), which are invariably described as 2D van der Waals materials with sheets of ligands connected by square planar or octahedral metal ions. Here, we employ electron diffraction to show that, unlike the Mg, Co, Ni, and Cu analogs, Zn3(HOTP)2 crystallizes into a three-dimensional network that is analogous to the structures of the lanthanide-based HOTP MOFs. Moreover, similar to the lanthanide frameworks, Zn3(HOTP)2 exhibits incommensurate modulation, likely originating from a frustration between the preferred π-π stacking distance and the Zn-O bond lengths, or from a Peierls distortion. This work reinforces the importance of employing single crystal diffraction measurements for the characterization of conductive MOFs, especially when trying to correlate electronic properties to structural details.

Organic optoelectronics are increasingly important due to their tunablilty, flexibility, and solution processability. Tuning optical properties of these materials as solids relies on the balance of weak non-covalent interactions that dictate crystal structure, but are difficult to predict. Our research aims to improve our understanding of how electrostatic interactions can direct and facilitate intramolecular interactions that dictate emergent properties of crystalline materials. This paper focuses on exploring how multi-fused thiophene ring systems that are popular in modern organic optoelectronic materials impact intramolecular interactions, while also investigating the role of molecular shape. In these examples, the shape of heterocyclic systems correlate with the crystal structures: while the bent heterocyclics show no discrete and discernable intramolecular interactions, those with bent shapes interact cofacially with one of the electron poor ArF pendants by twisting the arylene ethynylene backbone. Two of the control molecules, which bear non-fluorinated benzyl ester substituents, show intramolecular edge-face interactions, and several of these molecules show clear polymorphic behavior. These findings further our understanding of how discrete interactions can be altered not only by electrostatics, but also by shape, allowing for increasingly nuanced control over the crystal structures and optical properties of optoelectronic materials.