Water-Soluble
and
Cleavable
Photoinitiators:
A
Comparison
and
Characterization
Stephan BenediktI,*, Jieping WangII, Marica MarkovicIII,* Norbert MosznerIV, Kurt DietlikerII,
Aleksandr OvsianikovIII,*, Hansjörg GrützmacherII, and Robert LiskaI,*
I
Institute of Applied Synthetic Chemistry, Division of Macromolecular Chemistry (part of the CD-
Laboratory for digital and restorative dentistry), Vienna University of Technology, Getreidemarkt
9/163/MC, A-1060 Vienna, Austria
II
Department of Chemistry and Applied Biosciences, Swiss Federal Institute of Technology, Vladimir-
Prelog-Weg 1-5, CH-8093 Zurich, Switzerland
III
Institute of Materials Science and Technology, Vienna University of Technology, Getreidemarkt 9,
1060 Vienna, Austria
IV
IVOCLAR VIVADENT AG (part of the CD-Laboratory for digital and restorative dentistry),
Bendererstrasse 2, FL-9494 Schaan, Liechtenstein
*Austrian Cluster for Tissue Regeneration
Correspondence to: Robert Liska (Robert.Liska@tuwien.ac.at)
Supplementary Information
Synthesis
Na-TPO
The synthesis was done according to Noe et al.1 Trimethylbenzoylphenylphosphinacid ethylester
(Lucirin® TPO-L, BASF AG; 1.02 g, 3.22 mmol, 1 eq.) were dissolved in ethylmethylketone (5 mL). NaI
(0.53 g, 3.55 mmol, 1.1 eq.) was added and after 15 min. the homogenous solution was heated to
65°C and stirred for 24 h. The resulting yellow precipitate was filtered off and washed one time with
10 mL ethylmethylketone and two times with 10 mL PE. After drying in high vacuum the product was
recrystallized from diethylether to yield the product as yellowish powder (0.85 g, 2.74 mmol, 85 %, M
= 310.3 g mol-1).
Tm = 372.4°C
1
H-NMR (d6-DMSO, 298 K): δ [ppm] = 2.2 (s, 6 H), 2.25 (s, 3H), 6.6 (s, 2H), 7.3 (m, 3H), 7.6 (m, 2H)
31
P-NMR (d6-DMSO, 298 K): δ [ppm] = 10.8
Li-TPO
The
synthesis
was
performed
with
slight
changes
compared
to
Majima
et
al.2
Trimethylbenzoylphenylphosphinacid ethylester (Lucirin® TPO-L, BASF AG; 10.75 g, 33.99 mmol, 1
eq.) were dissolved in ethylmethylketone (150 mL). LiBr (11.81 g, 135.96 mmol, 4 eq.) was added and
after 15 min. the homogenous solution was heated to 65°C and stirred for 24 h. The resulting yellow
precipitate was filtered off and washed one time with 10 mL ethylmethylketone and two times with
10 mL PE. After drying in high vacuum the product was recrystallized from diethylether to yield the
product as white powder (9.9 g, 33.65 mmol, 99 %, M = 294.2 g mol-1).
Tm = 350.5 °C
1
H-NMR (CD3OD, 298 K): δ [ppm] = 2.12 (s, 6 H), 2.23 (s, 3H), 6.77 (s, 2H), 7.4 (m, 3H), 7.81 (t, 2H)
13
C-NMR (CD3OD, 298 K): δ [ppm] = 21.3, 128.5, 129.0, 129.1, 132.2, 134.0, 134.3, 135.1
31
P-NMR (d6-DMSO, 298 K): δ [ppm] = 11.1
BAPO-OH
The synthesis of BAPO-OH was performed similar to Mueller.3 Sodium metal (8.642 g, 375.9 mmol, 3
eq.) was reacted with red phosphorus (4.012 g, 125.6 mmol, 1 eq., 97 %) in the presence of
naphthalene (1.612 g, 12.56 mmol, 0.1eq.) in DME (60mL). A black suspension of Na3P was obtained
after gentle stirring at room temperature (r.t.) for 12 hours. Subsequent addition of tBuOH (12.00
mL, 125.6 mmol, 1 eq.) and two equivalents of 2,4,6-trimethylbenzoyl chloride (41.80 mL, 251.2
mmol, 2 eq.) yielded a yellow solution of sodium bis(mesitoyl)phosphide (NaP(COMes) 2). After
protonation with acetic acid (7.2 mL, 125.6 mmol, 1 eq.) HP(COMes)2 was obtained. Before the
oxidation to the final product a solvent change from dme to toluene (200mL) was carried out. The
salts NaCl and NaOAc were separated by filtration under an argon atmosphere. The flask was
protected from light in order to prevent decomposition of the target compound. Subsequently, 31.9
mL of aqueous H2O2 (314.0 mmol, .5 eq., 30%) were added to the solution at 0 °C over a period of 15
min. The mixture was allowed to slowly warm to r.t. and stirred vigorously for 12 h. A pale yellow
suspension of the product was obtained. The precipitated product was collected by filtration, washed
with hexane and dried under high vacuum to afford an off-white solid (yield: 87% based on P).
31
P-NMR(121.5MHz, C6D6, 298K) δ[ppm]= -1.276
31
P-NMR(121.5MHz, CDCl3, 298K) δ[ppm] = -1.860
31
P-NMR(121.5MHz, D3CCN, 298K) δ[ppm]= -2.460
31
P-NMR(121.5MHz, THF, 298K) δ[ppm]=-2.58
31
P-NMR(121.5 MHz, H2O, 298K) δ[ppm]= -1.03
1
H-NMR (C6D6, 298K) δ[ppm]= 2.13 (s, 6H, p-CH3Mes), 2.38 (s, 12H, o-CH3Mes), 6.65 (s, 4H, Mes-H),
9.15 (s, 1H, OH); 1H-NMR(CDCl3, 298K) δ[ppm]= 2.18 (s, 12H, o-H3Mes), 2.35 (s, 6H, p-CH3Mes), 6.84
(s, 4H, Mes-H), 7.23 (broad, 1H, OH)
13
C-NMR(75.5 MHz, CDCl3, 298K) δ[ppm]= 19.19 (s, o-CH3Mes), 21.30 (s, p-CH3Mes), 128.845 (d,
4JCP= 7.6 Hz, Mes C3,5), 135.29 (d, 2JCP= 46.81 Hz, Mes C1), 135.495 (d, 3JCP= 7.6 Hz, Mes C2,6),
140.755 (d, 5JCP=7.6Hz, Mes C4), 213.77 (d, 1JCP=98.15Hz, COMes)
31
P-1HHMQC(300.13, 121.49MHz, CDCl3, 298K), couplings are observed to all hydrogen atoms bound
to carbon atoms, no coupling observed to acidic proton of P-OH moiety
ESIMS[M+NH4]+m/z=376.1672
Tm = 133°C
IRν[cm-1]= 2917.76 (w, ar CH st), 2851.10 (w, P-OH st), 364.02 (w, POH comb), 1685.18 (w), 1664.70
(w, CO st), 1605.83 (w, ar C-C), 1447.14 (w), 1421.55 w), 201.43 (w, P-O st), 1145.12 (w), 996.76 (m,
P=O st),843.10 (m).
BAPO-ONa
Subsequently to BAPO-OH synthesis the BAPO-ONa synthesis can be performed: BAPO-OH (0.64 g,
.79 mmol, 1 eq.) was dissolved in ethanol (4 mL) in a 20 mL round-bottom flask. Sodium
hydrogencarbonate (0.15 g, 1.79 mmol, 1 eq.) was added and the mixture was stirred for 1 h at r.t..
The solvent was removed under vacuum to afford a yellow solid (0.67 g, 1.76 mmol, 98%).
31
P-NMR(202.49MHz, D2O, 298K) δ[ppm]= 1.73
1
H-NMR(500.23 MHz, D2O, 298K) δ[ppm]= .28 and 2.29 (s, 18H, o-and p-CH3Mes), 6.98 (s, 4H,
HarMes)
13
C-NMR(125.78MHz, D2O, 298K) δ[ppm]= 18.93, 19.47, 20.00, 20.50. 21.04 (s, CH 3Mes), 128.42,
128.78, 129.25, 129.59 (4 x d, 3JPC=12-15Hz, C2,6Mes), 135.13 (s, C3,5Mes), 137.88 (d,
2JPC=38.99Hz, C1Mes), 141.10 (s, C4Mes), 26.93 (d, 1JPC=103.14Hz, COMes)
IR2915.27 (w, r C-H), 1641.08 (m, C=O st), 1442.53 (w, ar C-C), 1231.25 (vs, P=O st), 1078.52 (vs, P-O
st), 935.97 (w), 90.15 (m), 844.33 (s)
ESI MS[M]-m/z = 357.1261
Tm >250°C
Literature
1.
Noe, R.; Beck, E.; Maase, M.; Henne, A. Patent DE10206096A1, 2003.
2.
Majima, T.; Schnabel, W.; Weber, W. Makromol. Chem. 1991, 192, 2307-2315.
3.
Mueller, G.; Zalibera, M.; Gescheidt, G.; Rosenthal, A.; Santiso-Quinones, G.; Dietliker, K.;
Grützmacher, H. Macromolecular Rapid Communications 2015.