Photolabile Protecting Groups: A Strategy for Making

Transcription

1 Electronic Supplementary aterial (ESI) for Polymer Chemistry. This journal is The Royal Society of Chemistry 217 Supporting Information: Photolabile Protecting Groups: A Strategy for aking Primary Amine Polymers by RAFT Nethmi De Alwis Watuthanthrige, Pierce Kurek and Dominik Konkolewicz Experimental Section aterials All reagents were obtained from commercial sources unless otherwise specified. All reagents were used as received unless otherwise specified. 2-Cyano-2-propyl benzodithioate (CPDB) was synthesized using a procedure outlined in the literature. 1 Synthesis of 2-nitrobenzylcyclohexyl carbamate Synthesis of 2-nitrobenzylcyclohexyl carbamate was done according to previously studied procedure. 2 1 H NR (3 Hz, CDCl 3 ) δ (m, 4H), 5.53 (s, 2H), 4.79 (d, J = 6.6 Hz, 1H), (m, 1H), (m, 11H). Deprotection of photo protective group from 2-nitrobenzylcyclohexyl carbamate In a typical deprotection of ONBCC, to an NR tube,.2g of ONBCC was dissolved in 1.mL of CDCl 3. Corresponding mixtures were irradiated with 31nm, 392nm, 44 nm, 52 nm and 63 nm wavelengths and analyzed through NR at h, 2 h, 4 h, 8 h, 16 h, and 24 h.

2 Synthesis of 2-{[(benzyloxy)carbonyl]amino}ethyl 2-methylprop-2-enoate (ONBAA): In a 1 ml two neck round bottom flask equipped with magnetic stirrer bar and a condenser, 2- nitrobenzylalcohol (2.5 g,.16 mol) and 2-isocyanatoethylmethacrylate (2.66 g,.17 mol) were added and dissolved in 5 ml toluene. The reaction mixture was deoxygenated for 15min and then temperature was increased up to 11 C over 1 hour. Subsequently, the temperature was maintained between 11 C-12 C for 1.5 h, after which time the reaction was stopped. ixture was then cooled to room temperature and precipitated with hexane to obtain off-white colored 2- {[(benzyloxy)carbonyl]amino}ethyl 2-methylprop-2-enoate monomer (ONBAA) (4.52 g,.15mol, 9% yield). The compound was confirmed through 1 H NR, 13 C NR, ESI/S analysis. 1 H NR (3 Hz, Chloroform-d) δ 8.14 (d, J = 8.2 Hz, 1H), (m, 3H), 5.9 (d, J = Hz, 2H), 5.57 (s, 2H), 5.2 (s, 1H), 4.3 (t, J = 5.3 Hz, 2H), 3.58 (q, J = 5.7 Hz, 2H), 1.99 (s, 3H). 13 C NR (126 Hz, CDCl 3 ) δ , , , 135.9, , , , , , , 77.29, 77.4, 76.78, 63.58, 63.45, 4.41, ESI/S=331.1(monomer + Na + )

3 Synthesis of poly 2-{[(benzyloxy)carbonyl]amino}ethyl methacrylate poly(onbaa) For a typical synthesis of poly(onbaa), to a 1 ml round bottom flask containing a stirrer bar, ONBAA (1.g, 3.25mmol), CPDB (.18g,.6mmol), and Azobis(isobutyronitrile) (AIBN) (.2g,.1mmol) were dissolved in 4 ml of toluene. The mixture was purged with N 2 for 15 min and then heated for 7 C for 24 h. Polymer was obtained by precipitation into hexane. Precipitated polymers were characterized by SEC. Deprotection of 2-nitro benzyl group from poly 2-{[(benzyloxy)carbonyl]amino}ethyl methacrylate Poly[ONBAA] (.6 g,.19 mmol ONBAA) and conc. HCl (.11 g,.29 mmol HCl) were dissolved with 1 ml of DSO. Solution was irradiated with 31 nm light in a NR tube and upon irradiation NR and SEC analysis were carried out at hr, 2 h,4 h, 8 h, 16 h, and 24 h of irradiation times. Prior to SEC analysis,.1 ml volume of deprotected amine solution was neutralized with.4 g (with equal moles of HCl moles in.1ml).

4 Analytical ethods Nuclear magnetic resonance (NR) Spectroscopy Nuclear magnetic resonance (NR) measurements were carried out using Bruker 3 and 5 Hz spectrometers. ass Spectrometry ESI-S spectra data were collected using positive ion mode of Bruker Esquire-LC mass spectrometer (Billerica, A). UV-Visible Spectroscopy UV measurements were collected using LABDA 75 UV/Vis/NIR Spectrophotometer Size exclusion Chromatography (SEC) Size exclusion chromatography (SEC) was performed to determine polymer molar mass data using an Agilent 126 SEC system equipped with an auto-sampler, an Agilent 126 isocratic pump, Agilent 1 guard and 2 analytical PolarGel- columns, degasser and Agilent 126 refractive index (RI detector). DF was used as the eluent at 25 C with a flow rate of 1 ml/min. All the samples were filtered before the injection to instrument. Size distribution and Zeta Potential measurements Size distribution measurements of the amine functionalized polymer was obtained using Zeta sizer ZEN16 Nano series instrument at 25 C. Zeta potential was measured using nanobrook ZetaPlus zeta potential analyzer. Each solution (1.3mg/mL) was passed through.22 μm filter. Photo reactor Characterization All the intensities of UV and visible light sources were determined using ThorLabs P1A light power meter. 3, 4

5 Supplemental Data Photoreactor data Table S1: Characterization for the Visible light (Violet, Blue, Green, and Red) 4 and Ultraviolet 3 photoreactors. The wavelength of peak emission (λ max ), Full width at half maximum (FWH), and power output intensity (I) are given. Uncertainty in λ max is estimated at half the FWH rounded to 1 significant figure, with a minimum uncertainty of 1 nm. 4 Reactor λ max (nm) FWH (nm) I (mw/cm 2 ) Ultraviolet 31 ± ± 5 Violet 39 ± Blue 44 ± Green 52 ± Red 63 ± UV-Visible Spectra Analysis A.25m 2-nitrobenzylcyclohexyl carbamate solution was prepared in chloroform and the UV- Visible spectra was measured over the time of irradiation to 31nm UV light. (min, 5min, 1min, 15min, 2min, 25min, 3min and 45min)

6 (A) 1 (B) 1 Absorbance min 5 min 1 min 15 min 2 min 25 min 3 min 45 min 6 min Wavelength/(nm) Deprotection Efficiency/(%) Time/(min) Figure S1: A). Changes in UV-Visible spectra of ONBCC upon irradiation under UV irradiation ( max = 31 2 nm, I = 49 5 mw/cm 2 ) over time (min, 5 min, 1 min, 15 min, 2 min, 25 min, 3 min 45 min and 6 min) at r.t, [ONBCC]=.25m. B). Kinetics measured by NR, of photochemical deprotection under UV irradiation ( max = 31 2 nm, I = 49 5 mw/cm 2 ) of ONBCC as a function of wavelength at r.t. [ONBCC] =.25 m. Table S2: Characterization of poly(onbaa) chains. Reaction Conditions, Time, Conversion, theoretical number averaged molar mass ( n-th ), experimental number averaged molar mass ( n ), and molar mass dispersity ( w / n ) values are given. [ONBAA]:[CPDB]:[AIBN] Time Conv. k p app n-th n w / n (h) (%) (h -1 ) (g/mol) (g/mol) Low 25:1: (L) edium 5:1: () High 1:1: (H)

7 A -ln(1-conversion) L H time/h B n (g/mol) n 5 5 L H Conversion 4 6 (%) 8 1 Conversion (%) w / n w / n Figure S2: A) Semi- logarithmic kinetic plot and B) Evolution of n (solid points), n-th (dashed line), and w / n (hollow points) with conversion. Conditions: [ONBAA]:[CPDB]:[AIBN] = X:1:.2, where X =1 for H, 5 for and 25 for L series, 1 g of ONBAA in 4 ml of toluene at 7 C. (A) (B) (C) x1 4 1x1 6 1x x1 4 1x1 6 1x x1 4 1x1 6 1x1 8 Figure S3: SEC molar mass distribution data for the poly(onbaa) 5 (6 mg/ml) over irradiation time (2 h, 4 h, 8 h, 16 h, 24 h) under UV irradiation ( max = 31 2 nm, I = 49 5 mw/cm 2 ); A) Initial solution in DSO with Amine functional groups: Acetic acid=1:1 ratio, B). Initial solution in DSO with Amine functional groups: Acetic acid=1:2 ratio, C). Initial solution in DSO with Amine functional groups: Acetic acid=1:1 ratio

8 (A) 1 (B) 2 (C) Deprotection efficiency/(%) Units 5 Units 1 Units t/(h) x x x x 1 6 Figure S4: a) Deprotection efficiencies of poly(onbaa) of 25, 5, and 1 unit long polymer chains at r.t the polymer (6 mg/ml) over irradiation time (2 h, 4 h, 8 h, 16 h, 24 h) under UV irradiation ( max = 31 2 nm, I = 49 5 mw/cm 2 ); b) SEC molar mass distribution data for the deprotection of initial solution of poly(onbaa) 25 in DSO with Amine functional groups: HCl=1:1.5 ratio, under UV irradiation ( max = 31 2 nm, I = 49 5 mw/cm 2 ) c). SEC molar mass distribution data for the deprotection of initial solution of poly(onbaa) 1 in DSO with Amine functional groups: HCl =1:1.5 ratio under UV irradiation ( max = 31 2 nm, I = 49 5 mw/cm 2 ). Volume/(%) units 5 Units 1 Units Size/(d.nm) Figure S5: DLS data for deprotected ammonium functional 25, 5 and 1 unit polymer chains after 24 h of irradiation with 31 nm light at r.t with Amine functional groups: HCl=1:1.5 ratio, concentration = 1.34 mg/ml.

9 References 1. D. Konkolewicz, B. S. Hawkett, A. Gray-Weale and S. Perrier, acromolecules, 28, 41, R. Winkle, US Pat., A, J. A. Reeves,. L. Allegrezza and D. Konkolewicz, acromol. Rapid Commun., 217, 38, L. Allegrezza, Z.. Deartini, A. J. Kloster, Z. A. Digby and D. Konkolewicz, Polym. Chem., 216, 7, 6626.