Molecular “Texas Longhorn”: An expanded Schiff base oligopyrrolic macrocycle

We report here the synthesis and structural characterization of a novel expanded Schiff base oligopyrrolic macrocycle TxLH (i.e. compound 2) along with its smaller congener hemi-TxLH (i.e. compound 1). The solid-state structure of TxLH is reminiscent of the shape of a Texas Longhorn[Formula: see text]. It thus defines a new architectural form for porphyrin analogues. The present study thus underscores the potential of using functionalized oligopyrroles as readily accessible molecular building blocks for the construction of structurally non-trivial molecules.

Silicon Phthalocyanines: Synthesis and resurgent applications

The intense far-red absorption and emission features have made silicon phthalocyanines (SiPcs) distinct from the structurally related porphyrin analogues. Unlike most other phthacyanines, SiPcs possess two additional axial bonds which...

Design, synthesis and comparison of water-soluble phthalocyanine/porphyrin analogues on inhibition of Aβ42 fibrillization

The misfolding and fibrillization of β amyloid (Aβ) is a major pathological hallmark of Alzheimer’s disease (AD) and creates an important niche for developing targeted probe and drug designs. Phthalocyanine...

A Brief Introduction to Porphyrin Compounds Used in Tumor Imaging and Therapies

Abstract:: As a group of heterocyclic macrocycle organic natural compounds occurring universally in animal tissues and plants, porphyrins are composed of four modified pyrrole subunits. Porphyrin analogues/derivatives possess multiple biochemical properties because of their unique structures and have been extensively investigated in cancer treatment. Studies have shown that porphyrins and their derivatives have the ability to locate in tumor cells in a variety of human cancers, and these compounds not only exhibit potent therapeutic effects as photodynamic agents but also show promising properties in medicinal imaging, such as MRI, photoacoustic imaging, fluorescence imaging and PET/SPECT imaging. This paper reviews the recent reports of porphyrin derivatives as therapeutic agents used in tumor therapies, such as sonodynamic therapy, photodynamic therapy and radiotherapy, as well as imaging agents for multimodality tumor imaging. The limitations of porphyrin-based compounds in tumor treatments and future prospects are also summarized.

Synthesis, Structure, and Magnetic Properties of Linear Trinuclear CuII and NiII Complexes of Porphyrin Analogues Embedded with Binaphthol Units

A porphyrin analogue embedded with (S)-1,1′-bi-2-naphthol units was synthesized without reducing optical purity of the original binaphthol unit. This new macrocyclic ligand provides the hexaanionic N4O4 coordination environment that enables a linear array of three metal ions. That is, it provides the square planar O4 donor set for the central metal site and the distorted square planar N2O2 donor set for the terminal metal sites. In fact, a CuII3 complex with a Cu(1)–Cu(2) distance of 2.910 Å, a Cu(1)–Cu(2)–Cu(1′) angle of 174.7°, and a very planar Cu2O2 diamond core was obtained. The variable-temperature 1H-NMR study of the CuII3 complex showed increasing paramagnetic shifts for the naphthyl protons as temperature increased, which suggests strong antiferromagnetic coupling of CuII ions. The temperature dependence of the magnetic susceptibility indicated antiferromagnetic coupling both for the CuII3 complex (J = −434 cm−1) and for the NiII3 complex (J = −49 cm−1). The linear (L)M(µ-OR)2M(µ-OR)2M(L) core in a rigid macrocycle cavity made of aromatic components provides robust metal complexes that undergo reversible ligation at the apical sites of the central metal.

Phthalocyanine-Cored Fluorophores with Fluorene-Containing Peripheral Two-Photon Antennae as Photosensitizers for Singlet Oxygen Generation

A series of free base and Zn(II) phthalocyanines featuring fluorenyl antennae linked by methoxy or oxo bridges to the phthalocyanine core (Pc) were synthesized and characterized. Selected linear and nonlinear (two-photon absorption) optical properties of these new compounds were subsequently studied. As previously observed for related porphyrin dendrimers bearing 2-fluorenyl peripheral dendrons, an efficient energy transfer occurs from the peripheral antennae to the central phthalocyanine core following excitation in the fluorenyl-based π–π* absorption band of these chromophores. Once excited, these compounds relax to the ground state, mostly by emitting intense red light or by undergoing intersystem crossing. As a result, the tetrafunctionalized Zn(II) phthalocyanines are fluorescent, but can also efficiently photosensitize molecular oxygen in tetrahydrofurane (THF), forming singlet oxygen with nearly comparable yields to bare Zn(II) phthalocyanine (ZnPc). In comparison with the latter complex, the positive role of the fluorenyl-containing antennae on one- and two-photon brightness (2PA) is presently demonstrated when appended in peripheral (β) position to the phthalocyanine core. Furthermore, when compared to known porphyrin analogues, the interest in replacing the porphyrin by a phthalocyanine as the central core to obtain more fluorescent two-photon oxygen photosensitizers is clearly established. As such, this contribution paves the way for the future development of innovative biphotonic photosensitizers usable in theranostics.