To a solution of 2,2 - dimethylpropan-1 - amine ( 0.60 mL , 0.44 g , 4.9 mmol ) in dry DMF ( 50 mL ) was added 6methyl-2-(bromomethyl)-pyridine 1 ( 2.00 g , 10.8 mmol ) and K 2 CO 3 ( 1.49 g , 10.8 mmol ) . The solution was stirred at 40 ° C for 16 h. The organic component was extracted into CH 2 Cl 2 ( 3 × 40 mL ) , the extract dried over MgSO 4 , filtered and the solvent was removed under reduced pressure . The product was purified using silica gel chromatography ( Hexane : EtOAc -10:1 ) to yield 1.28 g of L5 as a pale yellow solid ( 88 % ) .    Titration data and speciation curves of L2 and Zn complex 2 . Figure S3 . left : titration of 10 mL of 2 mM L2 and 4 mM HCl with 10 µL aliquots of 0.2 mM NaOH ; right : speciation diagram of 1mM L2 . The theoretical fit and speciation were carried out with Hyperquad and HySS software 3 and gave pK a s of 3.85 and 6.99 . Figure S4 . left : titration of 10 mL of 2 mM Zn complex 2 and 4 mM HCl with 10 µL aliquots of 0.2 mM NaOH ; right : speciation diagram of 1 mM 2 . The theoretical fit and speciation were carried out with Hyperquad and HySS software 3 using formation constants for Zn(OH ) ( 10 -7.84 ) and Zn(OH ) 2 ( 10 -16.86 ) taken from literature . 4 The fit gives pK a s for the Zn complex 2 of 7.84 and 9.02 , and log K d as 4.85 .   Observed rate constants ( k obs ) were obtained by the initial rate method over the first 30 minutes of the reaction . Equation S1 is derived from Scheme S1 , and fitted to the data in Tables S1 to S8 to give the values of k 2 used in Figure S5 .