Peripherally substituted tetradecaaza­heptacene (N14Hp) compounds, exhibiting amphiprotism-coupled emission, have been synthesized. X-ray crystallography reveals a planar acene-like chromophore, and electronic absorption and emission occur in the near-infrared biological transparency window (650–900 nm). The compounds exhibit long-wavelength emission with photoluminescence quantum yields ΦPL up to ∼0.61 at 686 nm, with the monodeprotonated state ΦPL ≈ 0.58 at 712 nm. This unprecedented highly nitrogenous chromophore illustrates the stability and utility of the pyrazinacenes for different applications based on their photophysical properties and chemical structures.

As eries of largely p-extended multichromophoric molecules including cross-conjugated, half cross-conjugated, conjugation-interrupted and linearly conjugated systems were synthesized and characterized.T hese multichromophoric molecular systems revealed interesting structural-property relationships.B isporphyrin-fused pentacenes Pen-1 b and Pen-2 a showed rich redox chemistry with 7a nd 8o bservable redox states,r espectively.T he linearly-conjugated bisporphyrin-fused pentacenes (Pen-1 b and Pen-2 a)p ossess much narrower HOMO-LUMO gaps (1.65 and 1.42 eV redox, respectively) and higher HOMO energy levels than those of their pentacene analogues (2.23 and 2.01 eV redox, respectively), similar to those of muchl ess stable hexacenes and heptacenes.A ne stimated half-life of > 945 hw as obtained for bisporphyrin-fused pentacene Pen-2 a,w hich is much longer than that of its pentacene analogue (BPE-P,h alf-life, 33 h).

Molecules that can exist in multiple states with the possibility of toggling between those states based on different stimuli have potential for use in molecular switching or sensing applications. Multimodal chemical or photochemical oxidative switching of an antioxidant-substituted resorcinarene macrocycle is reported. Intramolecular charge-transfer states, involving hemiquinhydrones are probed and these interactions are used to construct an oxidation-state-coupled molecular switching manifold that reports its switch-state conformation via striking variation in its electronic absorption spectra. The coupling of two different oxidation states with two different charge-transfer states within one macrocyclic scaffold delivers up to five different optical outputs. This molecular switching manifold exploits intramolecular coupling of multiple redox active substituents within a single molecule.

Push–pull opp-dibenzoporphyrins with a phenylethynyl bridge were newly synthesized as sensitizers for dye-sensitized solar cells, giving power conversion efficiencies up to 6.7%, close to that of the N719 dye under similar conditions.