Charles Michael Drain

Self-Organized Porphyrinic Materials

The self-assembly and self-organization of porphyrins and related macrocycles enables the bottom-up fabrication of photonic materials for fundamental studies of the photophysics of these materials and for diverse applications. This rapidly developing field encompasses a broad range of disciplines including molecular design and synthesis, materials formation and characterization, and the design and evaluation of devices. Since the self-assembly of porphyrins by electrostatic interactions in the late 1980s to the present, there has been an ever increasing degree of sophistication in the design of porphyrins that self-assemble into discrete arrays or self-organize into polymeric systems. These strategies exploit ionic interactions, hydrogen bonding, coordination chemistry, and dispersion forces to form supramolecular systems with varying degrees of hierarchical order. This review concentrates on the methods to form supramolecular porphyrinic systems by intermolecular interactions other than coordination chemistry, the characterization and properties of these photonic materials, and the prospects for using these in devices. The review is heuristically organized by the predominant intermolecular interactions used and emphasizes how the organization affects properties and potential performance in devices.

Porphyrin Tessellation by Design: Metal-Mediated Self-Assembly of Large Arrays and Tapes**

Twenty-one components self-assemble to form the large (ca. 25 nm2 ), planar porphyrin arrays of type 1: four dipyridylporphyrins, four tripyridylporphyrins, one tetrapyridylporphyrin, and twelve PdCl2 units.

Glycosylated Porphyrins, Phthalocyanines, and Other Porphyrinoids for Diagnostics and Therapeutics

for Diagnostics and Therapeutics Sunaina Singh,*,†,∥ Amit Aggarwal,*,†,∥ N. V. S. Dinesh K. Bhupathiraju,*,‡ Gianluca Arianna,‡ Kirran Tiwari,‡ and Charles Michael Drain‡,§ †Department of Natural Sciences, LaGuardia Community College of the City University of New York, Long Island City, New York 11101, United States ‡Department of Chemistry and Biochemistry, Hunter College of the City University of New York, New York, New York 10065, United States The Rockefeller University, New York, New York 10065, United States

Phthalocyanine Blends Improve Bulk Heterojunction Solar Cells

A core phthalocyanine platform allows engineering of the solubility properties the band gap, shifting the maximum absorption toward the red. A simple method for increasing the efficiency of heterojunction solar cells uses a self-organized blend of phthalocyanine chromophores fabricated by solution processing.

A perspective on four new porphyrin-based functional materials and devices

The tremendous potential for the manifold applications of porphyrins, porphyrazines, and phthalocyanines derives from their photophysical and electrochemical properties, their remarkable stability, and their predictable and rigid structure. These applications include nonlinear optics, catalysts, sensors, actuators, molecular sieves, and therapeutics. All of these properties are modulated by appending various chemical moieties onto the macrocycles, by choice of metallo derivative, and by the choice of environment. In multichromophoric systems, furthermore, the relative orientation of the chromophores, the nature of the linker, and the size of the system also dictate the properties. The synthesis of multichromophoric systems – both via covalent and noncovalent linkers – is driven by the desire to make new materials and to understand biological processes such as the various aspects of photosynthesis. Though electron and energy transfer processes continue to drive the synthesis of ever more complex systems, m...

Self-organization of self-assembled photonic materials into functional devices: Photo-switched conductors

Linear porphyrin arrays self-assembled by either hydrogen bonding or metal ion coordination self-organize into lipid bilayer membranes. The length of the transmembrane assemblies is determined both by the thermodynamics of the intermolecular interactions in the supermolecule and by the dimension and physical chemical properties of the bilayer. Thus, the size of the porphyrin assembly can self-adjust to the thickness of the bilayer. An aqueous electron acceptor is placed on one side of the membrane and an electron donor is placed on the opposite side. When illuminated with white light, substantial photocurrents are observed. Only the assembled structures give rise to the photocurrent, as no current is observed from any of the component molecules. The fabrication of this photogated molecular electronic conductor from simple molecular components exploits several levels of self-assembly and self-organization.

Synthesis and photophysical properties of thioglycosylated chlorins, isobacteriochlorins, and bacteriochlorins for bioimaging and diagnostics.

The facile synthesis and photophysical properties of three nonhydrolyzable thioglycosylated porphyrinoids are reported. Starting from meso-perfluorophenylporphyrin, the nonhydrolyzable thioglycosylated porphyrin (PGlc₄), chlorin (CGlc₄), isobacteriochlorin (IGlc₄), and bacteriochlorin (BGlc₄) can be made in 2-3 steps. The ability to append a wide range of targeting agents onto the perfluorophenyl moieties, the chemical stability, and the ability to fine-tune the photophysical properties of the chromophores make this a suitable platform for development of biochemical tags, diagnostics, or as photodynamic therapeutic agents. Compared to the porphyrin in phosphate buffered saline, CGlc₄ has a markedly greater absorbance of red light near 650 nm and a 6-fold increase in fluorescence quantum yield, whereas IGlc₄ has broad Q-bands and a 12-fold increase in fluorescence quantum yield. BGlc₄ has a similar fluorescence quantum yield to PGlc₄ (<10%), but the lowest-energy absorption/emission peaks of BGlc₄ are considerably red-shifted to near 730 nm with a nearly 50-fold greater absorbance, which may allow this conjugate to be an effective PDT agent. The uptake of CGlc₄, IGlc₄, and BGlc₄ derivatives into cells such as human breast cancer cells MDA-MB-231 and K:Molv NIH 3T3 mouse fibroblast cells can be observed at nanomolar concentrations. Photobleaching under these conditions is minimal.

Porphyrin nanoparticles as supramolecular systems

Certain applications of supramolecular porphyrinic systems, such as molecular sieves and photonics, rely on precise nanoarchitectural control of the molecules and/or atoms; therefore they require self-assembled systems of discrete arrays and highly ordered crystals. Other applications, such as oxidation catalysts for simple substrates, may be affected by the use of self-organized materials with less supramolecular order. Colloidal porphyrin nanoparticles can be considered self-organized systems that are governed by the principles of supramolecular chemistry. The formation and potential applications of nanoparticles of these chromophores are discussed in this report with special emphasis on the parameters in the methods used to make these materials, and in terms of the supramolecular chemistry. These principles, concepts, and methodologies are applicable to a wide variety of organic dyes. “Mais Dieu a choisi celuy qui est le plus parfait, c’est a dire celuy qui en meme temps le plus simple en hypotheses, et le plus rich en phenomenes.” Gottfried Leibniz.

Silica Nanoparticles as Substrates for Chelator-free Labeling of Oxophilic Radioisotopes

Chelator-free nanoparticles for intrinsic radiolabeling are highly desirable for whole-body imaging and therapeutic applications. Several reports have successfully demonstrated the principle of intrinsic radiolabeling. However, the work done to date has suffered from much of the same specificity issues as conventional molecular chelators, insofar as there is no singular nanoparticle substrate that has proven effective in binding a wide library of radiosotopes. Here we present amorphous silica nanoparticles as general substrates for chelator-free radiolabeling and demonstrate their ability to bind six medically relevant isotopes of various oxidation states with high radiochemical yield. We provide strong evidence that the stability of the binding correlates with the hardness of the radioisotope, corroborating the proposed operating principle. Intrinsically labeled silica nanoparticles prepared by this approach demonstrate excellent in vivo stability and efficacy in lymph node imaging.

Self-assembly of square multiporphyrin arrays by metal ion coordination

The complexation of cis or trans meso-dipyridyl porphyrins by cis or trans substituted metal ions (PdII, PtII) of square planar coordination geometry leads to the self-assembly of multiporphyrin arrays of square architecture.