Solubility Properties X-ray crystal structure of : dicyclohexyl[18]crown-6 and potassium complex of [18]crown-6. Structures are different: In the solid state In polar and apolar solvent As a complex 1
Solubility Properties Structure a is unrealistic, why? 2
Solution Applications 3
Solution Applications 4
Solution Applications X A K A Crown ether Reaction of potassium salts with benzyl chloride in acetonitrile (X= Cl, A= anion,e.g.acetate). Free, desolvated anions in organic solvents All anions have a similar nucleophilicity 5
Solution Applications 6
Selectivity of Cation Complexation 7
Selectivity of Cation Complexation 8
Selectivity of Cation Complexation 9
The template Effect 10
The template Effect 11
High-Dilution Synthesis Cyclization rate: r c = k c [X Y] Polymerization rate: r p = k p [X Y] 2 12
High-Dilution Synthesis Cl H 2 + C Cl High-dilution H 2 C H H C LiAlH 4 H H High-dilution synthesis of diaza(18)crown-6.ote the use of acid chloride groups to enhance reaction rate. 13
14 High-Dilution Synthesis H H 1+1 Fe Fe Cl Cl Fe Fe Fe Fe Fe (3.56) 3+3 Simultaneous(1+1),(2+2) and (3+3) cyclococondensation in bipyridyl-based cryptands 2+2 (3.54) (3.55) +
Kinetic and Dynamic Effects ne of the few kinetically stable complexes X-ray crystal structures of free spherand 3.30 and its Li + complex K = k 1 /k -1 k 1 = 8*10 4 (M -1 s -1 ) k -1 =<10-12 (s -1 ) total desolvation leads to a high transition state Cation receptor: slow kinetic, large stability constant Cation carriers: fast kinetic, lower stability 15
Soft Ligands for Soft Metal Ions 16
Soft Ligands for Soft Metal Ions 17
Soft Ligands for Soft Metal Ions 18
Soft Ligands for Soft Metal Ions 19
Soft Ligands for Soft Metal Ions 20
Soft Ligands for Soft Metal Ions X-Ray Crystal structures of the Ag + complexes of [18]crown-6 and its sulfur analogue 21
Soft Ligands for Soft Metal Ions Macrocycle Synthesis through Schiff s Bases Thermodynamic equilibrium Template effect H H H H i(cl 4 ) 2 i 2+ KC H H H 2 H 2 + H H H H + i(cn) 2-4 22
Soft Ligands for Soft Metal Ions + H 2 H 2 Mn 2+, Mg 2+ (a) Ba 2+, Pb 2+ (b) M + M + 23
Complexation of rganic Cations 24
Complexation of rganic Cations 3.78 3.79 3.80 25
Complexation of rganic Cations 26
Recognition of H 3+ (CH 2 ) n H 3 + 27
Calixarenes p-tert-butylcalix[4]arene Conformation Cone conformer is most effectively stabilised by intramolecular hydrogen bonds Interconversion is slow on the MR time scale at r.t. (ca 150 s -1 ), but readily observed at 60 C 28
Calixarenes n H H * CH 2 CH 2, H + * + * H CH 2 * CH 2 H n CH 2 Bakelite * CH 2 * H n R R R R R R R R HAc, HCl H C H 2 H C H 2 H C H 2 H C H 2 H H H H H calix[4]arene 29
Calixarenes 30
Calixarenes Conformational analysis by variable temperature MR (VT MR) Suitable for energies in range from 20 to 100 kj mol -1, typical error ±1 kj mol -1 Lower temperatures: separate peaks (process is kinetically slow on the MR time scale), broadening upon increase of temperature Coalescence temperature: peaks merge to single broad signal k c π ν = 2 k c = rate, ν = frequency separation between MR peaks (at lower temperature) k c k B T = e h k B = 1.3805 x 10-23 J K -1 (Boltzmann constant), h = 6.6256 x 10-34 J s (Planck s constant), T = absolute temperature (K), R = 8.314 J mol -1 K -1 (molar gas constant) # ΛG R T Higher temperatures: single signal becomes sharper 31
Calixarenes X- ray structures of a a + complex and a Cs + complex of calix[4]arene Two binding pockets: an hydrophobic And a spherand like 32
Calixarenes Fast intramolecular Ag + tunneling is observable by 1 H MR (coalescence temperature about -70 C) 33
Calixarenes 34
Calixarenes Bu Bu Bu Bu Bu Bu Bu Bu BIS(CALIX)CRWS Conformational aspects of cation inclusion Extraction experiments with picrates salts 1.Fast intramolecular cation exchange 2 days required for formation of the a komplex 2.Slow intermolecular cation exchange Bu Bu Bu Bu Bu Bu Bu Bu 35 Alkali metal intra- and intermolecular exchange processes
Carbon Donor and π-acid ligands 36
Carbon Donor and π-acid ligands 37
Carbon Donor and π-acid ligands 38
Siderophores 39
Siderophores Bu 2 Sn(C 2 H 4 ) 40
Siderophores 41