Growth of Hybrid Chiral Thin Films by Molecular Layer Deposition Zinc/Cysteine as a Case Study

Abstract

bio-mimic interfaces with enantioselective properties remains challenging for chemists and materials scientists. For many research areas, such as medicine, biology, and chemistry, achieving enantioselective control is essential because it is a key parameter in molecular recognition. [5][6][7] Hence, the development of advanced methods to synthesize, separate, and detect chiral compounds is of particular importance.Chirality also plays a useful role in many nanosystems, [8] such as chiroptical molecular switches, [9][10][11] molecular motors, chiral surfaces, [12,13] chiral nanoparticles, [14][15][16][17][18][19] and chiral polymeric nanoparticles. [20][21][22] Overall, the areas of chiral nanoscience and nanotechnology hold exceptionally strong promise for further developments in areas such as catalysis, biorecognition, and chiral separation. Chiral mesoporous materials, for example, chiral mesoporous carbon, [23,24] chiral mesoporous silica, [25][26][27] and silica imprinted with different chiral functionalities, [28][29][30][31] are examples of promising nanosystems and have proved to play an important role in many fields of chemistry.One of the most promising chiral nanoscale systems is based on the use of chiral surfaces. Overall, there are three types of chiral surfaces, including surfaces from chiral bulk structures, such as quartz, and some high Miller-index surfaces of achiral crystals. [14] Chiral surfaces can also be produced by templating using chiral ligands and by the adsorption of chiral molecules to form chiral self-assembled monolayers (SAMs). [32][33][34][35] A potentially promising method to produce chiral surfaces is molecular layer deposition (MLD), used in combination with atomic layer deposition (ALD). [36] The A/MLD (atomic/molecular layer deposition) method is based on bifunctional compounds that vaporize, chemisorb, and react with a suitably functionalized surface. Both ALD and MLD allow the temporal separation of any number of precursors, each of which undergoes a self-limiting adsorption/ reaction on the surface so that the typical uptake is limited to approximately one monolayer of any given precursor. The ALD and MLD system is the same. However, the difference between these two is by replacing the small oxidizing precursor (e.g., water, O 3 ) used for ALD with oxidizing organic molecule as the reactant. Therefore, it will grow molecular layer instead of growing atomic layer. This leads to a growth controlled at the Atomic and molecular layer deposition (ALD and MLD) are techniques based on surface-directed self-limiting reactions that afford deposition of films controlled at the monolayer level and with extreme conformality, even on ultra-high-aspect-ratio and porous substrates. These methodologies are typically used to deposit thin films with desirable physical properties and functionality. Here, the MLD process is harnessed to demonstrate the growth of molecularly thin chiral films that inherit a desirable chemical property directly from the source precursor: using this innovative t...

Atomic/Molecular Layer Deposition for Designer's Functional Metal–Organic Materials

“…245 [259] Bdy 1,4-Butynediol 50 [258] 4,4′-BPDC 4,4′-Biphenyldicarboxylic acid 250 [106] Aconitic acid 114 [234] 1,3-BDC 1,3-Benzenedicarboxylic acid 212 [114] EA Ethanolamine 80 [260,261] 1,3,5-BTC 1,3,5-Benzenetricarboxylic acid 245 [205] MC Malonyl chloride RT, [262] 28 [261] AZO 4,4′-Azobenzenedicarboxylic acid 310 [134,263] Lactic acid 115 [264] Cur Curcumin 260 [135,265] Pimelic acid 139 [221] 1,4-NDC 1,4-Naphthalenedicarboxylic acid 200 [266] DEG Diethylene glycol 100 [267] ADA 9,10-Anthracenedicarboxylic acid 240 [266] HD 1,6-Hexanediol 85 [125] Qz Quinizarin 130 [268] DD 1,10-Decanediol 120 [269] BDS 1,4-Benzenedisulfonic acid 190 [121] H 4 Pe Pentaerythritol 160 [268] DHTP 2,5-Dihydroxyterephthalic acid 190 [270] PD 1,3-Propanediol 100 [271] PMDA 1,2,4,5-Benzenetetracarboxylic anhydride 150 [209] l-Cys l-Cysteine [217,272] Abbreviation Full name (ring-opening) Source temperature [°C] l-Ala l-Alanine [217] Phenol 80 [273,274] l-Lys l-Lysine [217] 3F 3-(Trifluoromethyl)phenol 80 [273,274] Malonic acid 125 [221] 4F 2-Fluoro-4-(trifluoromethyl)benzaldehyde 60 [273,274] l-aspartic acid 225 [210] GLY Glycidol 60 [275,…”

“…Diethylzinc is the most common precursor for zinc in the ALD/MLD processes; it is often combined with HQ, [54,55,66,107,133,230,[244][245][246][247]250,361,366,[370][371][372][373][374][375][376][377][378] but also with many other organic components. [46,48,115,134,211,212,226,228,233,238,239,241,265,272,278,324,345,349,[379][380][381][382][383][384][385][386][387][388]…”

“…[ 31,32,39–44,176,181–200 ] In recent years, the organic precursor library has been rapidly expanding. We have collected in Table 1 the organic precursors so far used in ALD/MLD processes, together with the heating temperatures employed for their evaporation in the corresponding process conditions; [ 17,18,32,40,46,51,57–59,61,63,64,66,81,105–108,114,118,119,121,122,125,129,134–136,139,141,142,156,164,168,189,201–284 ...…”

“…Diethylzinc is the most common precursor for zinc in the ALD/MLD processes; it is often combined with HQ, [ 54,55,66,107,133,230,244–247,250,361,366,370–378 ] but also with many other organic components. [ 46,48,115,134,211,212,226,228,233,238, 239,241,265,272,278,324,345,349,379–390 ] The DEZ + HQ process has been widely utilized for the growth of different superlattice structures in which the Zn–HQ layers are combined with thicker ZnO layers grown with ALD cycles from DEZ plus H 2 O. Another zinc precursor employed in ALD/MLD is zinc acetate.…”

Atomic and Molecular Layer Deposition of Chiral Thin Films Showing up to 99% Spin Selective Transport

“…Previous attempts to deposit hybrid chiral films using molecular layer deposition utilized amino acids as molecular precursors with limited vapor pressure. 41,42 ■ DEPOSITION OF HYBRID ORGANIC−INORGANIC CHIRAL THIN FILMS Hybrid aluminum oxide-organic thin films with embedded chiral molecular precursors were prepared using trimethylaluminum (TMA) (Aldrich 97%), ultrapure water (>18 MΩ, ELGA purification system), L-alaninol or D-alaninol from TCI chemicals (98% purity) as precursors. Ar was used as a carrier gas in a hot wall reactor.…”