Controlled crystallization of twinned crystalline guanine microplatelets

Abstract

In this work, twinned anhydrous guanine β microplatelets were synthesized for the first time in the presence of a polyvinylpyrrolidone. The twinning angle of the two c axes for the synthetic and biogenic twinned guanine crystals is 84°, very similar to each other.

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

“…More interestingly, the angles between the two c axes were measured to take some specific angles, that is, approximately 45°, 63°, and 85° (Figure 3 e, j; see Figure S8 for the 63° case). These observations lead us to conclude that the as‐obtained cross‐shaped guanine crystals, SGmPs‐β (I) and SGmPs‐β (X), are twinned crystals with the (100) plane as the twinning plane, similar to our previous report [37] …”

“…This is achieved through a phase transformation of a hydrated amorphous guanine phase in an organic solvent, such as dimethyl sulfoxide, with the presence of polyvinylpyrrolidone (PVP) [36] . By using a mixed solvent of formamide and water with poly(1‐vinylpyrrolidone‐co‐vinyl acetate) (P(VP‐co‐VA)) as additive, twinned microplatelets with morphologies such as cross and square shapes can be obtained [37] . However, the synthesis of β‐AG microplatelets with (100) exposed plane with similar morphological and crystallographic control as in biological ones is still yet to be demonstrated.…”

“…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.…”

“…Similar SGmPs were obtained by replacing P(VP-co-VA) with another polymera dditive poly(1vinylpyrrolidone) (PVP) for aw ider ange of concentrations as well (0.01-10 mg mL À1 )( Figure S5). Due to the hydrophobic nature of the vinylpyrrolidone (VP)g roup, we hypothesize that P(VP-co-VA) and PVP may preferentially absorb onto the more hydrophobic (100) plane insteado fo ther planeso fA G, [36][37] which contributest ot he formation of the guaninem icroplatelets with (100) exposing planes.…”

“…These observations lead us to conclude that the as-obtained cross-shaped guanine crystals,S GmPs-b (I) and SGmPs-b (X), are twinned crystals with the (100) plane as the twinning plane, similar to our previousreport. [37] Lastly,w hen guanosine (GR) or adenine( A) was used during the synthesis, a phase SGmPs were obtained (Figure 4). Similar to otherc ases, the SGmPs synthesized with the presenceo fA and GR, despite the structurald ifferences, exhibit (100) exposing planesa ccording to the PXRD and SAED measurements (Figure 4a,f ,e ,j ).…”