Presentation on theme: "SYNTHESIS AND PROPERTIES OF SUPRAMOLECULAR COMPOUNDS ON THE BASE OF LAYERED DOUBLE HYDROXIDES Isupov V.P., Tarasov K.A., Chupakhina L.E., Mitrofanova R.P.,"— Presentation transcript:
SYNTHESIS AND PROPERTIES OF SUPRAMOLECULAR COMPOUNDS ON THE BASE OF LAYERED DOUBLE HYDROXIDES Isupov V.P., Tarasov K.A., Chupakhina L.E., Mitrofanova R.P., Starikova E.V. Institute of Solid State Chemistry and Mechanochemistry SB RAS Kutateladze-18, Novosibirsk, 630128 Novosibirsk State University, Pirogova-2, Novosibirsk, 630090 E-mail:firstname.lastname@example.org
General formula of layered double hydroxyde (LDH): [M(II) (1-X) M(III) X (OH) 2 ] Y+ (A n- Y/n ) mH 2 O M(II)= Mg 2+, Ni 2+, Co 2+, Zn 2+, Ca 2+, etc. M(III)=Al 3+, Cr 3+, Fe 3+, Mn 3+, etc. A n- - interlayer anions For Li + : [LiAl 2 (OH) 6 ] + n A n- ·mH 2 O Fig. 1. Structure of LDH with anions and water molecules in the interlayer space.
Methods of LDHs synthesis: Coprecipitation of LDH from basic solutions containing salts of M 2+ and M 3+ : (1-x)M(II) + xM(III) + 2(OH) - + Y/nA n- + mH 2 O = [M(II) (1-x) M(III) x (OH) 2 ] Y+ (A n- Y/n )·mH 2 O Topotaxial reactions Anion exchange method: [M(II) (1-x) M(III) x (OH) 2 ] Y+ (A n- Y/n )·mH 2 O +B m- [M(II) (1-x) M(III) x (OH) 2 ] Y+ (B m- Y/m )·nH 2 O + A n- Large amount of wastesPoor crystallinity of productsRestriction in the value of X in the product composition to the range 0,2-0,3
Direct intercalation Li + salts into the Al(OH) 3 Li n X + 2nAl(OH) 3 + mH 2 O = [LiAl 2 (OH) 6 ] n X·mH 2 O Fig. 2. Scheme of intercalation of Li salts into Al(OH) 3
Mechanochemical activation of mixture of hydroxides of divalent metals and salts of M 3+ 3Mg(OH) 2 + AlCl 3 6H 2 O = [Mg 2 Al(OH) 6 ]Cl nH 2 O + MgCl 2 (for example) Fig.3. Powder X-ray diffraction patterns of various samples: 1- initial Mg(OH) 2, 2-5 - products of mechanical treatment of Mg(OH) 2 with aluminium salts. Time of treatment - 3 min (2), 15 min (3,4,5). Aluminium salts- AlCl 3 6H 2 O (2,3), Al(NO 3 ) 3 9H 2 O (4), Al 2 (SO 4 ) 3 18H 2 O (5). 0 10 20 30 40 22
Interaction of dawsonite and salts of transition metals and Mg 2+ dawsonite NaAl(OH) 2 CO 3 – basic carbonate of sodium and aluminium or dawsonite Fig. 4. Interaction dawsonite with aqueous solution of Ni(NO 3 ) 2 (Ni/Al=0.5) 22
Probable scheme of interaction of dawsonite and Ni(NO 3 ) 2
Proposed methods of LDHs synthesis: Direct intercalation Li + salts into the Al(OH) 3 Mechanochemical activation of mixture of hydroxides of divalent metals and salts of M 3+ Interaction of dawsonite and salts of transition metals and Mg 2+
Fig.5. X-ray diffraction pattern: 1 - Li-Al-Cl, 2 - Li-Al-Co(edta), 3 - Li-Al-Cu(edta), 4 - Li-Al-Ni(edta). X-ray diffraction pattern of supramolecular compounds on the base of Li-Al layered double hydroxide
Scheme supramolecular system on the base of Li-Al LDH Fig. 6. Sheme of Li-Al-M(edta) without water molecules (1 - N, 2 - O, 3 - M, 4 - C)
Termal decomposition of [LiAl 2 (OH) 6 ] 2 [Medta]·mH 2 O (M=Ni 2+, Cu 2+, Сo 2+ ) (M=Ni 2+, Cu 2+, Сo 2+ ) LDH-Niedta (400 0 C) LDH-Cuedta (400 0 C) LDH-Coedta (450 0 C) Electron microscopic studies (SEM and TEM) of the products formed during thermal desomposition of the intercalates LiAl 2 (OH) 6 ] 2 [Cuedta]·4H 2 O and [LiAl 2 (OH) 6 ] 2 [Coedta]·4H 2 O showed that the decomposition is accompanied by the formation of nano- crystal metal particles with a size from 2 to 100 nm distributed chaotically both over the volume and on the surface of the amorphous oxide matrix. In the case of thermal decomposition of [LiAl 2 (OH) 6 ] 2 [Niedta]·4H 2 O, the size of the formed nano-sized nickel particles is close to 5 nm, their size disrtibution being very narrow. The mean distance between nickel particles in the amorphous matrix is 20 nm.
Conclusions 1. New methods of LDHs synthesis can be based on topotaxial reactions. 2. It have been shown a possibility of using the obtained LDHs as matrixes for preparation the supramolecular compounds with layered structure, containing complex anions: [M(edta)] 2- (M - Ni, Cu, Co, Zn, Pb, Mg, Mn), [Fe(edta)(OH)] 2-, [M(nta)] - (M - Ni, Cu, Co). 3. It have been shown a possibility of using the obtained LDHs as matrixes for preparation the composite materials containing nanosized particles of various metals. The investigation was supported by the Program "Scientific Research in Higher School into the Priority Directions of Science and Technology" (Grant N 3Н-118-01) and the Russian Foundation for Basic Research (Grant 02-03-32066).