William Ryan Osterloh

An antiaromatic expanded porphyrin self-assembles into a rectangular columnar liquid crystal. This enables intrinsic photoconductivity, reaching ϕ Σ µ values up to 5.8 × 10 ⁻⁴ cm ² V ⁻¹ s ⁻¹ upon doping.

Controlling interfacial charge-transfer (CT) interactions is a central challenge in two-dimensional (2D) organic–inorganic hybrid materials. Here, we show that molecular connectivity strongly governs excited-state evolution at a 2D heterointerface using anthracene (An) donors covalently attached to few-layer MoS2 nanosheets through an N-benzylsuccinimide linker at either the 2- or 9-position, generating two constitutional isomers, MoS2-2-An and MoS2-9-An. Ultrafast transient absorption spectroscopy reveals markedly different photodynamics that depend strongly on the donor attachment position. Photoexcitation of MoS2-2-An produces a long-lived interfacial CT excited state, whereas MoS2-9-An undergoes rapid formation of a full charge-separated state. The contrasting behavior is consistent with connectivity-controlled differences in donor orientation at the interface, which modulate orbital overlap and electronic coupling and may influence structural reorganization. Theoretical calculations further support that the more coplanar geometry of 2-An, exhibiting a calculated tilt angle (θ) of 29.5° relative to the MoS2 basal plane, enhances electronic coupling and stabilizes an intermediately coupled CT state, whereas the more upright 9-An orientation (θ = 42.1°) weakens orbital mixing and favors direct charge separation. These findings demonstrate that constitutional connectivity can serve as a molecular-level design parameter for tuning interfacial electronic coupling and directing excited-state evolution in 2D hybrid heterostructures relevant to optoelectronics, photocatalysis, and solar-energy conversion.

The integration of nitrogen atoms into chiral nanographenes (c-NGs) offers a powerful strategy for designing chiral materials with programmable electronic and chiroptical responses. However, the preparation of stable N-doped c-NGs featuring free NH groups─an essential chemical handle─remains a major synthetic challenge. Herein, we report a highly stable N-doped c-NG (NHNG) featuring a free NH moiety, which enables comprehensive investigation of not only its structural but also its optical, redox, electronic, and spintronic properties. X-ray crystallography reveals an intriguing π-scaffold combining three coexisting topologies: two helical and one saddle-shaped. By virtue of its extended conjugation, NHNG displays strong visible-light absorption (ε = 170,000 M^–1 cm^–1) and a rich electrochemical profile, with four oxidations leading to persistent cationic species that exhibit sharp near-infrared absorptions. In parallel, time-resolved microwave conductivity measurements demonstrate notable photoconductivity (ϕΣμ_max = 3.0 × 10^–5 cm² V^–1 s^–1). Owing to their robustness, the corresponding M- and P-enantiomers were resolved and found to exhibit pronounced chiroptical properties, with |g_abs| = 4.2 × 10^–3 and |g_lum| = 2.2 × 10^–3. Remarkably, both enantiomers also display spin-selective charge transport via the chiral-induced spin selectivity effect, reaching spin-polarization values of ∼80%─among the highest reported for single-molecule-based π-conjugated spin filters. Altogether, these findings render NHNG a multifunctional chiral platform for next-generation optoelectronic, spintronic, and chiroptical applications.

A phenothiazine (PTZ)‐zincporphyrin (ZnP)‐naphthalenediimide (NDI) triad was designed and synthesized to address the effects of electronic and vibrational excitations on photoinduced charge separation (CS) and charge recombination (CR). Upon photoexcitation, the singlet excited state of ZnP ( ¹ ZnP*) was generated and rapidly converted into a charge‐transfer (CT) state with partial excited‐state character, PTZ‐(ZnP ^δ+ ‐NDI ^δ– )*, in toluene, 1,2‐dichloroethane, and benzonitrile. In toluene, a secondary CT process from PTZ to (ZnP ^δ+ ‐NDI ^δ– )* produced a fully charge‐separated state, PTZ• ⁺ ‐(ZnP‐NDI)• ^– . This behavior arises from slower CR in nonpolar solvents, which proceeds in the Marcus inverted region due to weaker stabilization of the CT state and smaller reorganization energy. Additionally, enhancement and blueshift of the ethynyl stretching band (2100 cm ^–1 ) were observed in the excited states of PTZ‐ZnP‐NDI and ZnP‐ref, indicating the intrinsic contribution of ethynyl groups in the excited‐state of meso‐ethynyl‐substituted porphyrins. Simultaneous electronic and vibrational excitations did not influence the photoinduced CS and CR dynamics. These findings provide fundamental insights into manipulating charge‐transfer and charge‐separated states via external stimuli.

Covalent functionalization of two-dimensional (2D) transition-metal dichalcogenides is emerging as a powerful route to tailor interfacial photophysics for next-generation energy conversion schemes. Here we present monolayer molybdenum disulfide (MoS₂) covalently linked to pyrene (Py) and phenothiazine (PTz) units through phenylene (ph) and xylene (xy) bridges, affording the molecularly well-defined triads MoS₂-Py-ph-PTz and MoS₂-Py-xy-PTz. Ultrafast transient absorption spectroscopy, complemented by time-resolved electron paramagnetic resonance measurements, reveals that photoexcitation initiates interfacial charge-transfer (CT) excited states that subsequently dissociate to yield a long-lived MoS₂^•-/PTz^•+ charge-separated pair. Direct comparison of the phenylene and xylene bridge architectures shows that the rigidity and conformational freedom of the linker exert decisive control over electronic coupling and the kinetics of both CT and charge dissociation. These results establish a rare platform in which donor-acceptor distance, coupling strength, and CT dynamics at a 2D semiconductor interface can be tuned with molecular precision. Beyond elucidating the governing principles of interfacial CT in 2D-organic hybrids, this work demonstrates that covalent MoS₂-donor junctions can sustain long-lived charge separation reminiscent of processes central to organic photovoltaics. The modular design presented here opens clear avenues for constructing function-tailored 2D semiconductor architectures capable of directional charge flow, photoredox activity, and energy transduction, offering foundational insight for artificial photosynthesis, solar-fuel generation, and hybrid optoelectronic devices.

Ground-state and time-dependent density functional theory (TDDFT) calculations with the long-range-corrected, Coulomb-attenuating CAMY-B3LYP exchange-correlation functional and large, all-electron STO-TZ2P basis sets have been used to examine the potential "inverse hypercorrole" character of meso-p-nitrophenyl-appended dicyanidocobalt(III) corrole dianions. The effect is most dramatic for 5,15-bis(p-nitrophenyl) derivatives, where it manifests itself in intense NIR absorptions. The 10-aryl groups in these complexes play a modulatory role, as evinced by experimental UV-visible spectroscopic and electrochemical data for a series of 5,15-bis(p-nitrophenyl) dicyanidocobalt(III) corroles. TDDFT (CAMY-B3LYP) calculations ascribe these features clearly to a transition from the corrole's a(2u)-like HOMO (retaining the D-4h irrep used for metalloporphyrins) to a nitrophenyl-based LUMO. The outward nature of this transition contrasts with the usual phenyl-to-macrocycle direction of charge transfer transitions in many hyperporphyrins and hypercorroles; thus, the complexes studied are aptly described as inverse hypercorroles.

An unusual emissive charge-transfer excited state was formed at the pyrene–MoS ₂ interface.