MCD spectroscopy and TD-DFT calculations of low symmetry subnaphthalocyanine analogs

Bulking Up the Bay-Position Substituents Enables Enhanced Selectivity of Cs-Symmetric Boron Subphthalocyanine-Subnaphthalocyanine Hybrids

The precise synthesis of subporphyrinoid hybrids with π-expanded topologies and unique material properties plays a promising role in the design of functional macrocycles. Easy, selective, and controllable routes to boron subphthalocyanine-subnaphthalocyanine hybrids, Bsub(Pc3-p-Ncp)s, are desirable for this purpose yet synthetically challenging due to random mixtures of Cs-, C3v-, and, in some cases, C1-symmetric compounds that form during traditional statistical mixed cyclotrimerizations. Herein, we addressed this issue by developing a sterically driven mixed cyclotrimerization with enhanced selectivity for the targeted Cs-symmetric hybrid and complete suppression of sterically crowded macrocyclic byproducts. This process, coupled with a rationally designed precursor bearing bulky phenyl substituents, enabled the synthesis and characterization of bay-position phenylated Ph2-(Rp)8Bsub(Pc2-Nc1) hybrids with halogens (Rp = Cl or F) in their peripheral isoindole rings. Reaction selectivity ranged between 59 and 72% with remarkable yields, significantly higher than that of conventional mixed cyclotrimerizations. These findings were augmented by theoretical calculations on precursor Lewis basicity as guiding principles into hybrid macrocycle formation. Additionally, the incorporation of unfused phenyl groups and halogen atoms into the hybrid framework resulted in fine-tuned optical, structural, electronic, and electrochemical properties. This straightforward approach achieved improved selectivity and controlled narrowing of the product distribution, affording the efficient synthesis of structurally sophisticated Bsub(Pc2-Nc1) hybrids. This then expands the library of 3-dimensional π-extended macrocycles for use in a range of applications, such as in optoelectronic devices with precisely tailored optical properties.

Recent advances in subphthalocyanines and related subporphyrinoids

Subporphyrinoids constitute a class of extremely versatile and attractive compounds. Herein, a comprehensive review of the most recent advances in the fundamentals and applications of these cone-shaped aromatic macrocycles is presented.

Phenanthro[4,5-fgh]quinoxaline-Fused Subphthalocyanines: Synthesis, Structure, and Spectroscopic Characterization

A series of four phenanthro[4,5-fgh]quinoxaline-fused subphthalocyanine derivatives 0-3 containing zero, one, two, and three phenanthro[4,5-fgh]quinoxaline moieties, respectively, were isolated from the mixed cyclotrimerization reaction of 2,9-di-tert-butylphenanthro[4,5-fgh]quinoxaline-5,6-dicarbonitrile with 4,5-bis(2,6-diisopropylphenoxy)phthalonitrile and characterized by a series of spectroscopic methods including MALDI-TOF mass, (1) H NMR, electronic absorption, magnetic circular dichroism (MCD), and fluorescence spectroscopy. The molecular structures for the compounds 0 and 2 were clearly revealed on the basis of single-crystal X-ray diffraction analysis. Their electrochemical properties were also studied by cyclic voltammetry. In particular, theoretical calculations in combination with the electronic absorption and electrochemical analyses revealed the significant influence of the fused-phenanthro[4,5-fgh]quinoxaline units on the electronic structures.

Photophysical properties of tetraphenylporphyrinsubphthalocyanine conjugates

Novel tetraphenylporphyrin-subphthalocyanine conjugates have been prepared and characterized. An analysis of their optical spectroscopy and electronic structures using fluorescence emission and magnetic circular dichroism (MCD) spectroscopy and TD-DFT calculations, demonstrates that the two chromophores do not interact to any significant extent.

Photoisomerization and optical properties of a subphthalocyanine–azobenzene–subphthalocyanine triad

A novel subPc–AB–subPc triad exhibits on–off switching of the fluorescence emission intensity upon reversible trans ↔ cis photoisomerization of the azobenzene moiety. NMR spectroscopy provides additional evidence for the conformational change.