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Three symmetrically and three unsymmetrically substituted cibalackrot (7,14-diphenyldiindolo[3,2,1-de:3',2',1'-ij][1,5]naphthyridine-6,13-dione, 1) dyes carrying two derivatized phenyl rings have been synthesized as candidates for molecular electronics and especially for singlet fission, a process of interest for solar energy conversion. Solution measurements provided singlet and triplet excitation energies and fluorescence yields and lifetimes; conformational properties were analyzed computationally. The molecular properties are close to ideal for singlet fission. However, crystal structures, obtained by single-crystal X-ray diffraction (XRD), are rather similar to those of the polymorphs of solid 1, in which the formation of a charge-separated state followed by intersystem crossing, complemented with excimer formation, outcompetes singlet fission. Results of calculations by the approximate SIMPLE method suggest which ones among the solid derivatives are the best candidates for singlet fission, but it appears difficult to change the crystal packing in a desirable direction. We also describe the preparation of three specifically deuteriated versions of 1, expected to help sort out the mechanism of fast intersystem crossing in its charge-separated state.

BackgroundTotal annual cancer rates have decreased due to improved treatment and prevention. However, the incidence of melanoma is rising, and not all patients respond to immune and targeted approaches. Therefore, we sought to determine the efficacy of red light (RL) phototherapy in preclinical models of melanoma.MethodsMelanoma cells (A375, B16F10, MNT-1) were irradiated with RL. Melanoma proliferation, apoptosis, oxidative stress, and p53 phosphorylation were measured in vitro. In C57BL/6 mice, phototherapy safety, B16F10 tumor growth, and immunocyte infiltration were assessed following RL.ResultsIn vitro, 640 J/cm2 RL decreased cellular proliferation without increasing apoptosis, while 1280 J/cm2 increased apoptosis. RL increased intracellular reactive oxygen species generation and p53 phosphorylation. In animal models, 2560 J/cm2 RL significantly prevented melanoma growth and increased the expression of CD103+ dendritic cells. 1280 and 1920 J/cm2 RL decreased tumor volume, but not significantly. RL did not cause skin inflammation or erythema in normal skin.ConclusionRL represents a potentially safe and effective melanoma therapeutic. RL prevented tumor growth and increased the expression of immune markers, such as CD103, that are associated with favorable melanoma outcomes. Further research is needed to determine the optimal clinical treatment regimen for melanoma using RL.

Pyridine-terminated molecular rods and either (i) the cis-(dppp)(I)Pt(CC-triptycene-CC)Pt(I)(dppp) rod or (ii) the trans-(PEt3)2(I)Pt(CC-biphenyl-CC)Pt(I)(PEt3)2 rod assemble into macrocycles, characterized by NMR, ESI-IMS, and in two cases also single-crystal X-ray diffraction. The former form rectangles with bidentate phosphine-containing cis-coordinated Pt(II)-alkyne corners. In the latter, the preference of the Pt centers for a trans configuration overrules the preference of the triple bonds for linearity and NMR shows that they have oval structures with alternating bent rod and bent trans (CC)Pt(PEt3)2(CC) components, in agreement with density functional theory calculations.

We report an investigation of structure and photophysics of thin layers of cibalackrot, a sturdy dye derived from indigo by double annulation at the central double bond. Evaporated layers contain up to three phases, two crystalline and one amorphous. Relative amounts of all three have been determined by a combination of X-ray diffraction and FT-IR reflectance spectroscopy. Initially, excited singlet state rapidly produces a high yield of a transient intermediate whose spectral properties are compatible with charge-transfer nature. This intermediate more slowly converts to a significant yield of triplet, which, however, does not exceed 100% and may well be produced by intersystem crossing rather than singlet fission. The yields were determined by transient absorption spectroscopy and corrected for effects of partial sample alignment by a simple generally applicable procedure. Formation of excimers was also observed. In order to obtain guidance for improving molecular packing by a minor structural modification, calculations by a simplified frontier orbital method were used to find all local maxima of singlet fission rate as a function of geometry of a molecular pair. The method was tested at 48 maxima by comparison with the ab initio Frenkel-Davydov exciton model.

In situ grazing-incidence X-ray scattering shows that a monolayer of artificial rod-shaped dipolar molecular rotors produced on the surface of an aqueous subphase in a Langmuir trough has a structure conducive to a 2D ferroelectric phase. The axes of the rotors stand an average of 0.83 nm apart in a triangular grid, perpendicular to the surface within experimental error. They carry 2,3-dichlorophenylene rotators near rod centers, between two decks of interlocked triptycenes installed axially on the rotor axle. The analysis is based first on simultaneous fitting of observed Bragg rods and second on fitting the reflectivity curve with only three adjustable parameters and the calculated rotor electron density, which also revealed the presence of about seven molecules of water near each rotator. Dependent on preparation conditions, a minor and variable amount of a different crystal phase may also be present in the monolayer.

Dielectric spectroscopy has been used to determine the barriers of rotation of surface-mounted fullerenes (2.3 ± 0.1 and 4.3 ± 0.1 kcal mol−1). In order to achieve this, a C60 derivative equipped with an anchoring group designed to form a surface inclusion with the hexagonal form of tris(o-phenylenedioxy)cyclotriphosphazene (TPP) has been synthesized. Solid-state NMR analysis revealed that approximately 50% of the surface-mounted molecules have a chemical environment different from the others suggesting two distinct insertion modes. These observations correlate with results of DFT calculations. [ABSTRACT FROM AUTHOR]