Saber Mirzaei

Linker isomerism represents a powerful, yet unexploited, strategy for programming framework topology and unlocking chemical complexity in high-connectivity reticular systems. Here, we demonstrate the reticular synthesis of two 12-connected nanographene-based zirconium metal–organic frameworks, MOF-1300 and MOF-1400, wherein network architecture is directed by the meta versus para carboxylate substitution patterns of a 12-connected linker, dodeca-carboxylate hexakis[3,5-bis(m/p-carboxyphenyl)-4,6-dimethoxyphenyl]hexabenzocoronene (m/p-HBC-LH12). The meta isomer directs the assembly of an 8-connected cubic Zr cluster to yield MOF-1300 with an unprecedented trinodal (3,6,8)-c rcb1 net, representing a new topology in reticular chemistry. Conversely, the para isomer enforces 12-connectivity at the Zr cluster with hexagonal prismatic geometry to yield MOF-1400 with a rare trinodal (3,6,12)-c kex net which has not previously been observed in Zr-MOFs. Beyond structure, both frameworks serve as solid reservoirs of photoactive nanographenes: under basic photoredox conditions, they release their molecular HBC linkers, which act as homogeneous organophotoredox catalysts for the hydrodefluorination of polyfluoroarenes under simulated solar light (AM 1.5G). This behavior highlights the potential of reticular materials as precatalysts for the delivery of molecular photocatalysts and provides a basis for exploring such materials in future photocatalytic applications.

Resolving and controlling the local dynamical properties of covalent organic frameworks (COFs) remains a central challenge, particularly when assembled from large, flexible building units. Here, we combine synchrotron X-ray pair distribution function (PDF) analyses with machine learning-accelerated molecular dynamics (MD) simulations to resolve the local structure and dynamics of two three-dimensional imine-linked COFs, COF-682 [(DHP)(TAM)]imine, assembled from 6,13-dihydropentacene (DHP) and tetrakis(4-aminophenyl)methane (TAM), and COF-612 [(HBC-LA12)(HAPT)2]imine, assembled from nanographene dodecabenzaldehyde hexakis[3,5-bis(p-formylphenyl)-4,6-dimethoxyphenyl]hexabenzocoronene (HBC-LA12) and 2,3,6,7,14,15-hexa(4-aminophenyl)triptycene (HAPT). Validated against the experimental PDFs through ensemble-averaged calculations, the simulations show that the exposed π-surface and V-shaped geometry of the DHP linker endow COF-682 with enhanced local flexibility through face-to-face and offset π-stacking interactions differing in both their average interplanar separation and their ring-plane tilt angle. In contrast, the extended nanographene linker rigidifies COF-612 by maintaining the planarity of its fused cores, while the linker pendant aryl rings equip both COFs with enhanced librational ability. The simulations further provide quantitative measures of the translational and reorientational mobility of the linkers, revealing how local COF dynamics may be tuned by balancing noncovalent interactions and different degrees of aromatic rigidity. The PDF-MD experimental-computational approach holds promise as a general method beyond conventional crystallography to gain insights into the local properties of COFs with the aim of directing their dynamic function.

Shape-persistent pyrene-embedded macrocycles remain scarce, and tubular conjugated molecules with intrinsic donor–acceptor (D–A) character have only recently emerged, largely within [n]cyclo-para-phenylene-based systems. Here we introduce a structurally distinct pyrene-containing nanotube (Pyr4), synthesized through a templated approach using an n-pentyl resorcin[4]arene, in which pyrene units and quinoxaline walls form an integrated D–A framework. Upon light excitation, Pyr4 displays behavior consistent with internal charge-transfer (ICT) between the pyrene donor (D) and the quinoxaline acceptor (A). The analogue with tolyl groups replacing pyrene (Tol4) shows markedly weaker D–A behavior. This assignment is supported by electrochemical studies, frontier molecular orbital analysis, and fluorescence solvatochromism, where emission shifts bathochromically by roughly 100 nm from 468 nm in hexane to 564 nm in DMSO. The fluorescence quantum yield (ϕf) falls with increasing solvent polarity, consistent with a stabilized charge-transfer state. In DCM, Pyr4 emits at 528 nm (ϕf = 0.2), red-shifted relative to previously reported pyrene-containing conjugated macrocycles.

The expansion of reticular chemistry into increasingly complex architectures relies on the precise translation of molecular geometry into extended crystalline frameworks. Here, we report the design and synthesis of a dodeca-benzaldehyde-functionalized nanographene (hexakis[3,5-bis(p-formylphenyl)-4,6-dimethoxyphenyl]hexabenzocoronene, HBC-LA₁₂), a molecule that integrates hexagonal and triangular shapes into a dodecatopic hexagonal prismatic geometry. The reticulation of HBC-LA₁₂ with 6-connected triangular prismatic and 4-connected square-planar linkers yields two single-crystalline three-dimensional imine-linked covalent organic frameworks, termed COF-612 [(HBC-LA₁₂)(HAPT)₂]_imine and COF-412 [(HBC-LA₁₂)(PyTTA)₃]_imine. The structure of these frameworks realizes the previously inaccessible (3,6,6)- and (3,4,6)-connected networks in COFs, corresponding to the kez and cez topologies, respectively. These nets represent unprecedented edge-2-transitive architectures derived from the parent (6,12)-connected alb and (4,12)-connected shp nets. Gas-sorption analysis reveals that these frameworks possess permanent porosity with Brunauer-Emmett-Teller surface areas exceeding 5000 m² g^-1. This work demonstrates the incorporation of nanographenes into three-dimensional imine-linked COFs, yielding the highest-connectivity single-crystalline COFs with novel kez and cez underlying nets and the highest porosity reported for COFs to date.

The crystallization of covalent organic frameworks (COFs) into single crystals remains a fundamental challenge, particularly beyond 4-connected tetrahedral nodes toward higher-connectivity building units. Here, we report the rapid synthesis of three tripty cene-based single-crystalline COFs (COF-563, -564, and -565) under mild conditions within 24 hours. By employing rigid 6-connected trigonal prismatic triptycene-based building units, hexakis(4-aminophenyl/4-formylphenyl)triptycene (Trip-NH 2/Trip-CHO), we access a topological regime of 3D COFs that includes the established hea and stp nets as well as an unprecedented (6,6)-connected htp topology. These frameworks are constructed through reticulation of the triptycene nodes with tetrahedral (tetra(4-anilyl)methane (TAM)), rectangular (pyrene-1,3,6,8-tetraaniline (PyTTA)), and hexagonal (hexakis(4′-formyl-[1,1′-biphenyl]-4-yl)benzene (HFBB)) complementary linkers to yield the hea, stp,

Access to highly strained molecules remains a challenge. We report the synthesis of a bench-stable and highly strained (∼135 kcal mol ⁻¹ ) deep cavitand.

Dioxygen binding solely through non-covalent interactions is rare. In living systems, dioxygen transport takes place via iron or copper-containing biological cofactors. Specifically, a reversible covalent interaction is established when O₂ binds to the mono or polynuclear metal center. However, O₂ stabilization in the absence of covalent bond formation is challenging and rarely observed. Here, we demonstrate a unique example of reversible non-covalent binding of dioxygen within the cavity of a well-defined synthetic all-Cu(I) tetracopper cluster.

Although reticular chemistry has commonly utilized mutually embracing tetrahedral metal complexes as crossing points to generate three-dimensional molecularly woven structures, weaving in two dimensions remains largely unexplored. We report a new strategy to access 2D woven COFs by controlling the angle of the usually linear linker, resulting in the successful synthesis of a 2D woven pattern based on chain-link fence. The synthesis was accomplished by linking aldehyde-functionalized copper(I) bisphenanthroline complexes with bent 4,4'-oxydianiline building units. This results in the formation of a crystalline solid, termed COF-523-Cu, whose structure was characterized by spectroscopic techniques and electron and X-ray diffraction techniques to reveal a molecularly woven, twofold-interpenetrated chain-link fence. The present work significantly advances the concept of molecular weaving and its practice in the design of complex chemical structures.

Naturally sourced 2-picolinic acid was discovered as an off-the-shelf, non-toxic, and inexpensive HBD catalyst for the cycloaddition of CO ₂ to both internal and terminal epoxides to prepare cyclic carbonates at low catalyst loadings.