Binary ionic porphyrin nanosheets: electronic and light-harvesting properties regulated by crystal structure

Abstract

Crystalline solids self-assembled from anionic and cationic porphyrins provide a new class of multifunctional optoelectronic micro- and nanomaterials. A 1 : 1 combination of zinc(II) tetra(4-sulfonatophenyl)porphyrin (ZnTPPS) and tin(IV) tetra(N-methyl-4-pyridiniumyl)porphyrin (SnTNMePyP) gives porphyrin nanosheets with high aspect ratios and varying thickness. The room temperature preparation of the nanosheets has provided the first X-ray crystal structure of a cooperative binary ionic (CBI) solid. The unit cell contains one and one-half molecules of aquo-ZnTPPS(4-) (an electron donor) and three half molecules of dihydroxy-SnTNMePyP(4+) (an electron acceptor). Charge balance in the solid is reached without any non-porphyrinic ions, as previously determined for other CBI nanomaterials by non-crystallographic means. The crystal structure reveals a complicated molecular arrangement with slipped π-π stacking only occurring in isolated dimers of one of the symmetrically unique zinc porphyrins. Consistent with the crystal structure, UV-visible J-aggregate bands indicative of exciton delocalization and extended π-π stacking are not observed. XRD measurements show that the structure of the Zn/Sn nanosheets is distinct from that of Zn/Sn four-leaf clover-like CBI solids reported previously. In contrast with the Zn/Sn clovers that do exhibit J-aggregate bands and are photoconductive, the nanosheets are not photoconductive. Even so, the nanosheets act as light-harvesting structures in an artificial photosynthesis system capable of reducing water to hydrogen but not as efficiently as the Zn/Sn clovers.

Modulation of the cooperativity in the assembly of multistranded supramolecular polymers

“…[21][22][23] For these polymers, small environmental changes (including changes in pH, temperature or salt concentration [24][25][26] ) may modify the nucleation the development of nano-scale optical and electronic devices. 16,18,27 Their spectroscopic properties make them also ideally suited to study in detail mechanisms of supramolecular polymerization. [28][29][30] We have recently described the assembly of cobalt metalloporphyrin C and bipyridine B.…”

Pressure‐Tuned Structure and Property of Optically Active Nanocrystals

“…For example, molecular nanocrystals are formed through self-assembly of a single molecular precursor as a building block via covalent or noncovalent interactions including π-π stacking, hydrophobichydrophobic interaction, ligand coordination, etc. [ 1,2,4 ] The properties of the molecular nanocrystals result as a synergy not only from their individual building blocks but also from collective effects due to molecular coupling within the selfassembled nanocrystals. To manipulate the former, one can modify the molecular building blocks or compositions so as to tune the property of individual nanocrystals.…”

“…[ 1 ] Briefl y, a 0.5 mL of 0.01 M ZnTPP acidic solution (0.2 M HCl) was added into a 9.5 mL of basic surfactant solution containing 0.02 × 10 −3 M NaOH with Nanocrystals with unique morphology are relevant to a wide variety of optical and electronic applications such as photocatalysis, sensing, etc. [1][2][3][4] Precise control of structural parameters through nanoscale engineering to improve optical and electronic properties of functional nanocrystals continuously remains an outstanding challenge. Previous work has been conducted largely at ambient pressure and relies on specifi c chemical or physical interactions such as van der Waals interactions, dipole-dipole interactions, chemical reactions, ligand-receptor interactions, etc.…”

“…[4][5][6][7] Recently, there are signifi cant interests in using external forces as an effective means to control nanomaterial phases and structures for designing and engineering nanomaterials. [ 8 ] Quan et al reported reversal of Hall-Petch Effect in structural stability of nanocrystals and associated variation of phase transformation depending on nanocrystal sizes.…”

Assembly of π‐Conjugated Nanosystems for Electronic Sensing Devices

“…can also be used to fabricate the well-defined π-conjugated compound materials by simply mixing host solvent with guest solvent without additional help, those aggregations have been wildly applied for detecting target analyst. [65,[72][73][74][75][76][77] Thanks to these advantages, organic electronics are currently becoming comparable to or even in sometimes beginning to surpass corresponding inorganic photoelectric devices not only in their performances but also with respect to their cost.…”