Morphology and orientation control of guanine crystals: a biogenic architecture and its structure mimetics

Abstract

The surface skin of a banded blue-sprat had the mesocrystal structures of biogenic guanine crystals and cytoplasm. The platy guanine crystals were organized in the parallel direction to the surface skin with incorporation of cytoplasm. The size of the platy guanine crystal as a unit was larger than that of the other fish. Inspired by the biogenic structures, we studied the morphology and orientation control of molecular crystals consisting of organic molecules. When guanine was recrystallized on a glass substrate in the absence of any organic molecules, an aggregate of the platy crystals arranged perpendicular to the substrate was formed. The morphology and orientation of recrystallized guanine were different from those of the biogenic one. We have applied biomimetic approaches to control the morphology and orientation of the molecular crystals. The thin platy guanine crystals were formed parallel to the chitosan substrate through the recrystallization in the presence of additive organic molecules. The additive organic molecules and the modified substrates facilitated the morphology and orientation control. The present results suggest that biomimetic approaches for the morphological control of inorganic and ionic crystals can be applied for controlled deposition of a variety of organic and molecular crystals.

Nitrogen-carbon graphite-like semiconductor synthesized from uric acid

“…6, were in agreement with that of crystalline UA. This further supports that the starting material (UA) would be still present in considerable amounts in samples treated below 600 °C (the XRD pattern of CN450 was almost identical to that of anhydrous uric acid) [37]. Moreover, the XRD pattern of CN600-1 corresponded to a quite amorphous material with a broad peak around 27°, which seems to result directly from the UA peak at 27°, provided that the basic layered features of the original structure would be preserved (topotactic transformation).…”

Multiple heteroatom-doped few-layer carbons for the electrochemical oxygen reduction reaction

“…This molecule has a strong tendency to form molecular aggregates held together by in-plane hydrogen bonds and out-of-plane stacking interactions between the aromatic rings. [36][37][38][39][40] The current study, for the rst time, demonstrates the utilization of guanine as the carbon precursor that unprecedentedly facilitates the formation of ultrathin and large-scale 2D carbon nanosheets with naturally high-level nitrogen doping. Moreover, the combination of guanine with a dopant-containing acidic solution can give rise to formation of dopant-containing ionic compounds which, aer pyrolysis, are transformed into multiple-heteroatomdoped (N/S/O, N/P/O, and N/S/P/O) 2D carbons.…”

Synthesis of Bio‐Inspired Guanine Microplatelets: Morphological and Crystallographic Control

“…An umber of previouss tudies aimed to achieve similarc ontrol of the polymorph and morphology of guanine crystalssyntheticallyi nt he last years. [34][35][36][37][38] Utilizing chitosans ubstrates in the presence of poly(l-glutamic acid), Oaki et al synthesized a thin layer of aggregates of platy AG crystals,w hile it is unclear whether the synthesized AG is a or b phased ue to the low quality of X-ray diffraction patterns. [35] Gur et al demonstrated the polymorph controlb etween GM and AG by controlling the pH in the aqueous environment.…”