Metallated porphyrins containing lead(II), copper(II) or zinc(II)

Article abstract of DOI:10.1016/S0040-4020(02)00110-2

A series of ethynyl and aryl substituted porphyrins and the corresponding metallated derivatives have been synthesised and characterised.

Full text of DOI:10.1016/S0040-4020(02)00110-2

TETRAHEDRON
Pergamon
Tetrahedron 58 42002) 2415±2422
Metallated porphyrins containing leadꢀII), copperꢀII) or zincꢀII)
M. John Plater,a,p Stuart Aikena and Grant Bourhillb,²
aDepartment of Chemistry, University of Aberdeen, Meston Building, Room G103, Meston Walk, Aberdeen, Scotland AB24 3UE, UK
bDefence Science and Technology Laboratory, Great Malvern, St Andrews Road, Worcs WR14 3PS, UK
Received 24 October 2001;revised 19 December 2001;accepted 24 January 2002
AbstractÐA series of ethynyl and aryl substituted porphyrins and the corresponding metallated derivatives have been synthesised and
characterised. q 2002 Elsevier Science Ltd. All rights reserved.
1. Introduction
concentrated solutions. 43,5-Bis-tert-butylphenyl)-2,20-
dipyrrylmethane 67 was prepared by condensation of 3,5-
di-tert-butylbenzaldehyde 7 with pyrrole using pyrrole as
the solvent and tri¯uoroacetic acid as an acid catalyst.
Porphyrins 8, 9 and 11 were prepared by reaction of
dipyrrylmethane 6 with 3-trimethylsilylprop-2-ynal 1,
3-triisopropylsilylprop-2-ynal 2 or 3-phenylprop-2-ynal 5,
respectively, using BF3´OEt2 as catalyst.7±10 The inter-
mediate hexahydroporphyrins are oxidised in situ with
DDQ. Some care with the length of reaction time is required
because facile scrambling of meso ring substituents can
occur.8,11 Our studies with silylated acetylenes showed
that a reaction time of just 1 min was adequate before the
addition of DDQ. This short reaction time minimised
porphyrin by-products and aided puri®cation. During the
synthesis of porphyrin 9 a small quantity of 5,10,15-tris-
43,5-bis-tert-butylphenyl)-20-triisopropylsilylethynyl-
porphyrin 10 was isolated. The isolation of a similar inter-
mediate has been reported previously.8 Porphyrin 12,
substituted with two 4-nitrophenylethynyl groups, was
prepared by demetallation of the corresponding zinc metal-
lated derivative 13 with concentrated HCl. The synthesis of
this compound has been reported previously by us.12 Tetra-
ethynyl substituted porphyrins 14 and 15 were prepared by
condensation of pyrrole with 3-triisopropylsilylprop-2-ynal
2 and the branched silylpropynal 4, respectively, by
modi®cation of a literature procedure.13,14 Tetraphenyl-
porphyrin 16 was purchased and tetra-44-methoxyphenyl)-
porphyrin 17 was prepared in a similar manner to
compounds 14 and 15 using 4-methoxybenzaldehyde and
pyrrole.
Optical limiters or reverse saturable absorbers are materials
which display diminishing transmittance with increasing
incident light intensity. This attenuation of the optical
throughput can be used to protect various sensors against
damage from pulsed laser sources.1±5 Porphyrins and
phthalocyanines are promising candidates for certain
applications. Population of triplet excited states is
desirable since triplet states are longer lived than singlet
states which enhances the limiter's performance. Hence
dyes which contain heavy atoms are of interest because
heavy atoms can promote intersystem crossing. This paper
reports the synthesis and characterisation of a range of
porphyrins and their metallated derivatives containing
Zn4II), Cu4II) or Pb4II). The properties of lead porphyrins
in particular are of interest owing to the large size of the lead
atom.
2. Results and discussion
Porphyrins 8±9, 11±12 and 14±17 were synthesised by
documented methods. Modi®cations to some procedures
are described in Section 3. The silylprop-2-ynal building
blocks 1,6a 26b and 4 required for porphyrin synthesis were
prepared by treatment of the corresponding silylacetylene
with ethylmagnesium bromide followed by quenching with
DMF. 3-4Dimethyl-2-dodecyl-hexadecylsilyl)-propynal 4
has a large and branched alkyl side chain which was desired
to make low melting porphyrins that would not aggregate in
Keywords: porphyrins and analogues;palladium and compounds.
Corresponding author. Tel.: 144-1224-272-927;fax: 144-1224-272-921;e-mail: m.j.plater@abdn.ac.uk
Fax: 144-1865-747719.
p
²
0040±4020/02/$ - see front matter q 2002 Elsevier Science Ltd. All rights reserved.
PII: S0040-4020402)00110-2

2416
M. J. Plater et al. / Tetrahedron 58 12002) 2415±2422
Table 1. Summary of UV data for metallated porphyrins
Porphyrin
l
max, nm 4log e, 1000 cm2 mol21
)
18 4Zn)
194Cu)
204Pb)
214Zn)
234Pb)
244Pb)
254Zn)
264Pb)
274Pb)
284Pb)
294Pb)
43845.7)
43245.8)
47345.3)
44745.6)
47745.4)
48545.3)
46345.7)
50045.8)
50045.8)
35344.8)
46845.2)
44945.5)
60944.6)
49345.3)
65144.7)
49745.3)
73944.9)
65644.4)
71944.9)
71944.9)
46545.6)
76644.8)
63744.7)
70444.6)
72044.8)
65644.3)
Sharp Soret and Q bands help to create a good visible
window. These studies show that symmetric porphyrins
often have sharper absorption peaks than unsymmetric
porphyrins. For example, the lead containing metallo-
porphyrins 20 and 23 each have a split soret band whereas
symmetric metalloporphyrins 26±29 have a single Soret
band. The synthesis of [10,20-bis-43,5-bis-tert-butyl-
phenyl)-5,15-bis-ethynylporphinato] zinc4II) 22 has been
reported previously. The peaks are sharp for tetraphenyl-
porphyrin 28 containing lead but are broadened for
44-methoxytetraphenyl)porphyrin 29 which is substituted
with methoxy groups. The lead containing metallo-
porphyrins show a red shifted Q band maximum typically
in the region 700±720 nm. The 1H NMR spectra of some of
the lead containing metalloporphyrins shows that the lead
atom is situated off centre from the mean plane of the
porphyrin ring and that the meso aryl rings are suf®ciently
crowded to make rotation slow on the NMR time scale. For
example, in metalloporphyrins 20 and 24 the 3,5-di-tert-
butylphenyl groups show a peak for the two para hydrogens
and two broad singlets for the ortho hydrogens. Compounds
23 and 24 show two different tert-butyl groups.
The metallated porphyrins 18±21 and 23±29 were easily
prepared by heating the corresponding porphyrin with either
Zn4OAc)2, Cu4OAc)2 or Pb4OAc)2 in DMF. The UV±VIS
data are summarised in Table 1. The UV±VIS spectrum for
each porphyrin is important for optical limiting applications
because a visible window is required so it is undesirable to
have a strong ground state absorption in the visible region.

M. J. Plater et al. / Tetrahedron 58 12002) 2415±2422
2417
Alkyl silanes were purchased from Aldrich. Units of e are
1000 cm2 mol21
.
3.1.1.
3-Trimethylsilylprop-2-ynal
1.6a
General
procedure. Ethylmagnesium bromide, prepared from Mg
40.25 g, 10 mmol) and EtBr 41.1 g, 10 mmol) in THF
440 mL), was added dropwise to a solution of trimethylsilyl-
acetylene 41 g, 10 mmol) in THF 440 mL), under argon.
After the addition, the solution was re¯uxed for 5 min and
then added dropwise to a solution of DMF 44.5 g, 61 mmol)
in THF 440 mL). The solution was re¯uxed for 5 min before
dilute aqueous HCl 420 mL) was added. The solution was
poured into water and extracted with Et2O. The solution was
dried over MgSO4 and the solvent removed under reduced
pressure. The resulting oil was puri®ed by vacuum distilla-
tion to give the title compound 40.92 g, 72%) as a colourless
oil, bp 44±478C 420 mmHg) dH 4250 MHz;CDCl ) 0.16
3
49H, s, Si±Me) and 9.06 41H, s, CHO).
3.1.2. 3-Triisopropylsilylprop-2-ynal 2.6b 411.4 g, 78%) as
a pale yellow oil. dH 4250 MHz;CDCl ) 1.07±1.10 421H,
3
m) and 9.20 41H, s, CHO); dC 462.9 MHz;CDCl ) 11.0,
3
18.4, 100.8, 104.5 and 176.6.
3.1.3. 13-ꢀDimethylethynylsilylmethyl)heptacosane 3.
Method 1. Ethynylmagnesium bromide was prepared by
bubbling dry acetylene through a solution of EtMgBr,
prepared from magnesium 4160 mg, 6.6 mmol) and EtBr
41.0 g, 9 mmol), in THF 415 mL), for 1 h. This solution
was added to 13-4chlorodimethylsilylmethyl)heptacosane
43.0 g, 6 mmol) in THF 415 mL). After re¯uxing for
10 min the solvent was removed under reduced pressure
and the residue puri®ed by ¯ash chromatography on silica
using light petroleum 60±80 as eluent. The third fraction
was collected and the solvent removed under reduced
pressure to give the title compound 41.2 g, 42%) as a colour-
less oil. Method 2. A suspension of sodium acetylide 410 g,
18% w/w in xylenes, 37 mmol) was added to a stirred solu-
tion of 13-4chlorodimethylsilylmethyl)heptacosane 47.0 g,
14 mmol) in THF 430 mL) under argon. The solution was
stirred overnight before water was added to quench the
excess acetylide. The solution was extracted into Et2O
43£50 mL). The combined ethereal extracts were dried
over MgSO4 and the solvent removed under reduced pres-
sure. The residue was puri®ed by ¯ash chromatography on
silica using light petroleum 60±80 as eluent. The third frac-
tion was collected and the solvent removed under reduced
pressure to give the title compound 44.7 g, 69%) as a colour-
less oil. 4Found: C, 80.8;H, 13.5. C 32H64Si requires C, 80.6;
H, 13.5%); dH 4250 MHz;CDCl 3) 0.18 46H, s, Me±Si), 0.65
42H, d, CH2±Si, Jˆ7 Hz), 0.88 46H, m, Me), 1.25 448H, bs,
CH2), 1.55 41H, m, CH) and 2.36 41H, s, CC±H); dC
462.9 MHz;CDCl 3) 20.8, 14.2, 21.1, 22.7, 26.5, 29.8,
30.0, 32.0, 34.0, 36.4, 90.1 and 93.3 420 resonances are
missing).
The X-ray single crystal structures of lead containing metal-
loporphyrins 20 and 26 were solved. Full details of the
structures will be published elsewhere.15 The lead atoms
in each are situated out of the plane of the porphyrin ring
and are disordered in a similar manner. The replacement of
the four twisted meso aryl rings with ethynyl spacers and
the out of plane lead atom, might cause aggregation of
this porphyrin in concentrated solution by a stacking
phenomenon.
In summary a range of metallated porphyrins have been
prepared in which the absorption maxima are varied by
the choice of substituent and metal ion. Further properties
of these compounds will be reported in due course.
3.1.4. 3-ꢀDimethyl-2-dodecyl-hexadecylsilyl)-propynal 4.
42 g, 52%) as a pale yellow oil 4Found: C, 77.9;H, 13.25.
C33H64OSi requires C, 78.5;H, 12.8%); dH 4400 MHz;
CDCl3) 0.21 46H, s, Si±Me), 0.69 42H, d, Jˆ6.8 Hz, Si±
CH2), 0.82 46H, t, Jˆ4.1 Hz, Me), 1.25 448H, bs, CH2), 1.55
41H, m, CH) and 9.12 41H, s, CHO); dC 4100.6 MHz;
CDCl3) 20.5, 15.1, 21.6, 23.7, 23.7, 27.5, 30.4, 30.5,
3. Experimental
3.1. General
For general details see the preceding paper in this series.12

2418
M. J. Plater et al. / Tetrahedron 58 12002) 2415±2422
30.7, 30.7, 31.0, 32.9, 33.0, 35.0, 37.4, 103.7, 104.4 and
177.5 415 resonances are missing); m/z 4EI) 503.4 4M1,
100%).
BF3´Et2O 40.1 mL) was added to a stirred solution of aryl-
dipyrrylmethane 6 4753 mg, 2.2 mmol) and 3-triisopropyl-
silylprop-2-ynal 2 4500 mg, 2.4 mmol) in CH2Cl2 41 L) and
the solution stirred. After 1 min, DDQ 40.768 g, 3.4 mmol)
was added and stirring continued for a further 20 min. The
solution was ®ltered through silica, the solvent removed
under reduced pressure and the residue chromatographed
on silica with light petroleum/dichloromethane 41:1) as
eluent. The second fraction was collected and the solvent
removed under reduced pressure to give the title compound
4230 mg, 20%) as a purple crystalline solid, mp.3008C
4dichloromethane/methanol). Larger preparations of this
compound can be puri®ed by repeated crystallisation.
4Found: C, 79.2;H, 9.0;N, 5.0. C 70H94N4Si2´CH3OH
3.1.5. ꢀ3,5-Bis-tert-butylphenyl)-2,20-dipyrrylmethane 6.7a
The method is similar to the literature procedure but with
some modi®cations. Tri¯uoroacetic acid 40.1 mL) was
added to a stirred solution of 3,5-di-tert-butylbenzaldehyde
7 45.0 g, 23 mmol) in pyrrole 4250 mL, 3.6 mol). Stirring was
continued for 5 min, the solution diluted with CH2Cl2
4500 mL), washed with NaOH 41 M, 200 mL), dried over
Na2SO4 and the solvent removed under reduced pressure.
Excess pyrrole was removed by vacuum distillation at 408C
and the tarry residue puri®ed by ¯ash chromatography on
silica with hexane/ethyl acetate/triethylamine 480:20:10) as
eluent. The second fraction was collected and dissolved in hot
MeOH/water and stored at 2208C for 2 h. The solvent was
decanted into water and extracted into CH2Cl2. The organic
layer was dried over MgSO4 and the solvent removed under
reduced pressure at room temperature and the resulting oil
stored at 2208C for 5 days to give the title compound 45.5 g,
72%) as a pale yellow crystalline solid, mp 107±1088C 4hot
methanol/water) 4lit.7a 106±1078C). lmax4CHCl3)/nm 395
4log e 2.9) and 466 42.6); nmax 4KBr)/cm21 3417vs, 3396vs,
3101m, 2961vs, 2904m, 2865m, 1595m, 1564m, 1472m,
1425m, 1395m, 1361m, 1304w, 1246m, 1188w, 1112m,
1092m, 1030m, 972w, 902w, 881m, 779m, 757w, 714vs,
requires C, 79.0;H, 9.15;N, 5.2%);
lmax4CHCl3)/nm 434
4log e 5.7) and 585 44.9); nmax 4KBr)/cm21 2959vs, 2862s,
2139m, 1591m, 1558w, 1473m, 1427w, 1363m, 1263w,
1245m, 1136m, 1069m, 985m, 915m, 881m, 801s, 715s,
676m and 580w; dH 4250 MHz;CDCl 3) 22.11 4s, 2H,
N±H), 1.42 442H, m, i-Pr), 1.53 436H, s, t-Bu), 7.80 42H,
t, Jˆ1.8 Hz, p-Ph), 8.01 44H, d, Jˆ1.8 Hz, o-Ph), 8.86 44H,
d, Jˆ4.6 Hz) and 9.64 44H, d, Jˆ4.6 Hz); dC 462.9 MHz;
CDCl3) 11.9, 19.1, 31.8, 35.1, 99.1, 100.9, 108.8, 121.4,
123.1, 129.4, 130.4, 131.9, 140.4 and 148.9 4two resonances
are missing); m/z 4FAB) 1047 4M1, 100%).
3.1.8. 5,10,15-Tris-ꢀ3,5-bis-tert-butylphenyl)-20-triisopro-
pylsilylethynylporphyrin 10. Produced as an acidolysis
645w, 568m and 538m; dH 4400 MHz;CDCl ) 1.26 418H,
3
s, t-Bu), 5.42 41H, s, meso), 5.91 42H, bs), 6.13 42H, m), 6.65
42H, m), 7.04 42H, d, Jˆ1.7 Hz, o-Ph), 7.29 41H, t, Jˆ1.7 Hz,
p-Ph) and 7.89 42H, bs, N±H); dC 4100.6 MHz;CDCl 3) 32.5,
35.9, 45.6, 108.2, 109.4, 118.0, 121.9, 123.8, 134.0, 141.9
and 152.0.
product of
9
and separated by chromatography,
mp.2508C; lmax4CHCl3)/nm 426 4log e 5.4) and 565
44.6); nmax 4KBr)/cm21 3414w, 2958vs, 2863m, 1590m,
1469m, 1360m, 1245m, 1066w, 983w, 912w, 881w,
800m, 727m and 691w; dH 4250 MHz;CDCl ); 22.28 4s,
3
2H, N±H), 1.50 475H, m, t-Bu and i-Pr), 7.79 43H, m), 8.50
46H, m), 8.81 46H, m) and 9.70 42H, d, Jˆ4.9 Hz); dC
462.9 MHz;CDCl 3) 11.9, 19.1, 31.8, 35.1, 98.0, 99.0,
109.1, 121.2, 122.3, 123.3, 129.5, 132.2, 140.9, 141.2,
148.7 and 148.8 411 resonances are missing); m/z 4FAB)
1055.7326 4M1, C73H95N4Si requires 1055.7371).
3.1.6. 5,15-Bis-ꢀ3,5-bis-tert-butylphenyl)-10,20-bis-tri-
methylsilylethynylporphyrin 8.9 The procedure is similar
to that given in Ref. 9. Under argon, BF3´Et2O 425 mL) was
added to a solution of 43,5-bis-tert-butylphenyl)-2,20-
dipyrrylmethane 6 4168 mg, 0.5 mmol) and 3-trimethyl-
silylprop-2-ynal 1 463 mg, 0.5 mmol) in CH2Cl2 450 mL)
and the solution stirred at rt for 1 min. DDQ 4178 mg,
0.78 mmol) was added and stirring continued for 5 min
more. Et3N 41 mL) was added and the solution ®ltered
through silica. The solvent was removed under reduced
pressure and the residue, dissolved in light petroleum
60±80/CH2Cl2 41:1), was ®ltered through a short plug of
silica. The solvent was removed under reduced pressure to
give the title compound 444 mg, 20%) as a purple crystalline
solid, mp.2508C 4dichloromethane/methanol) 4Found: C,
77.4;H, 8.1;N, 6.4. C 58H70N4Si2´CH3OH requires C, 77.7;
3.1.9. 5,15-Bis-ꢀ3,5-bis-tert-butylphenyl)-10,20-bis-phenyl-
ethynylporphyrin 11. Method 1. A solution of aryl-
dipyrrylmethane 6 4310 mg, 0.9 mmol) and 3-phenylprop-
2-ynal 5 4120 mg, 0.9 mmol) in CH2Cl2 450 mL) was added
to a stirred solution of BF3´Et2O 40.1 mL) in CH2Cl2
4300 mL) under argon. Stirring was continued for 2 h,
DDQ 4316 mg, 1.4 mmol) was added and stirring continued
for a further 10 min. The solution was ®ltered through silica,
the solvent removed under reduced pressure and the residue
chromatographed on silica using light petroleum/CH2Cl2
41:1) as eluent. The solvent was removed under reduced
pressure and the residue crystallised from CH2Cl2/MeOH
to give the title compound 420 mg, 5%) as purple needles.
Method 2. Concentrated aqueous HCl 40.5 mL) was added
to a stirred solution of porphyrin 27 4400 mg, 0.42 mmol) in
THF 440 mL). The resultant brown solution was added to
Et2O 4100 mL) and the ethereal solution washed with
aqueous NaOH 4100 mL, 5 M), water, dried over MgSO4
and the solvent removed under reduced pressure. The
residue was dissolved in CH2Cl2 and ®ltered through silica.
MeOH was added and the product allowed to crystallise by
slow evaporation to give the title compound 4350 mg, 95%)
as purple needles, mp.2508C 4dichloromethane/methanol).
H, 8.2;N, 6.2%);
lmax4CHCl3)/nm 433 4log e 5.6); nmax
4KBr)/cm21 3314w, 2959vs, 2925m, 2866m, 2140m,
1591m, 1557w, 1474m, 1363m, 1246s, 1137w, 849vs,
798s and 719m; dH 4250 MHz;CDCl 3) 22.12 4s, 2H,
N±H), 1.55 436H, s, t-Bu), 7.82 42H, t, Jˆ1.9 Hz, p-Ph),
8.03 44H, d, Jˆ1.9 Hz, o-Ph), 8.86 44H, d, Jˆ4.8 Hz) and
9.60 44H, d, Jˆ4.8 Hz); dC 462.9 MHz;CDCl ) 0.3, 31.8,
3
35.1, 100.6, 102.4, 107.1, 121.3, 123.2, 129.9, 130.5br,
131.9br, 140.3 and 149.1 4two resonances are missing);
m/z 4FAB) 879 4M1, 100%).
3.1.7. 5,15-Bis-ꢀ3,5-bis-tert-butylphenyl)-10,20-bis-tri-
isopropylsilylethynylporphyrin
9.
Under
argon,

M. J. Plater et al. / Tetrahedron 58 12002) 2415±2422
2419
l
max4CHCl3)/nm 438 4log e 5.7) and 597 44.4); nmax 4KBr)/
410 mL) was added to a stirred solution of pyrrole 466 mg,
1 mmol) and 3-4dimethyl-2-dodecyl-hexadecylsilyl)-prop-
2-ynal 4 4495 mg, 1 mmol) in DCM 420 mL), cooled to
2308C. After 2 h the solution was allowed to warm to rt,
stirred for a further 2 h and DDQ 4167 mg, 0.74 mmol)
added. Stirring was continued for 10 min before the solution
was ®ltered through silica. The solvent was removed under
reduced pressure and the residue puri®ed by ¯ash chromato-
graphy on silica using light petroleum/CH2Cl2 49:1) as
eluent. The green band was collected and the solvent
removed under reduced pressure to give the title compound
cm21 2960vs, 2900m, 2865m, 1591s, 1555w, 1472s, 1426w,
1393w, 1362m, 1249s, 1155m, 1067w, 986w, 913m, 882w,
799vs, 751m, 726s and 686m; dH 4250 MHz;CDCl 3) 21.90
42H, s, N±H), 1.56 436H, s, t-Bu), 7.54 46H, m), 7.84 42H, t,
Jˆ1.5 Hz, p-Ph), 8.05 44H, m), 8.08 44H, d, Jˆ1.5 Hz,
o-Ph), 8.90 44H, d, Jˆ4.9 Hz) and 9.71 44H, d,
Jˆ4.9 Hz); dC 462.9 MHz;CDCl ) 31.8, 35.1, 92.2, 97.1,
3
100.9, 121.4, 123.4, 124.0, 128.8, 123.0, 131.7, 140.4 and
149.1; m/z 4FAB) 887.5062 4M11H. C64H63N4 requires
887.5052), 887.5 4M11H, 100%).
441 mg, 12%) as
a deep green amorphous solid;
lmax4CHCl3)/nm 449 4log e 5.6), 607 44.9) and 708 44.4);
dH 4250 MHz;CDCl ) 21.73 42H, s, N±H), 0.23 48H, d,
3
3.1.10. 5,15-Bis-ꢀ3,5-bis-tert-butylphenyl)-10,20-bis-ꢀ4-
nitrophenylethynyl)porphyrin 12. Concentrated aqueous
HCl 41 mL) was added to a stirred solution of [5,15-bis-43,5-
bis-tert-butylphenyl)-10,20-bis-44-nitrophenylethynyl)-
porphinato]zinc4II) 1312 45 mg, 0.5 mmol) in THF 440 mL).
The resultant solution was added to CH2Cl2 4100 mL),
washed with aqueous NaOH 4100 mL, 5 M), water, dried
over MgSO4 and the solvent removed under reduced
pressure. The residue was dissolved in DCM and ®ltered
through silica. MeOH was added and the product allowed
to crystallise by slow evaporation to give the title compound
40.45 g, 95%) as a purple powder, mp.3008C 4dichloro-
methane/methanol); lmax4CH2Cl2)/nm 449 4log e 5.4) and
607 44.5); nmax 4KBr)/cm21 719w, 792m, 848w, 1103w,
1151m, 1247m, 1332vs, 1469m, 1511m, 1587s, 2186m,
2861m, 2900m, 2954s, 3415s, 3478m and 3552m; dH
4250 MHz;CDCl 3) 22.07 42H, s, N±H), 1.67 436H, s,
t-Bu), 7.86 42H, s, br), 7.92 44H, s, br), 8.08 44H, s, br),
8.30 44H, s, br), 8.92 44H, s, br) and 9.57 44H, s, br); dC
Jˆ7.6 Hz, Si±CH2), 0.63 424H, s, Si±Me), 0.86 424H, t,
Jˆ8.2 Hz, Me), 1.27 4192H, bs, CH2), 1.95 44H, m, CH)
and 9.53 48H, s, b-pyrrolic); dC 462.9 MHz;CDCl ) 20.3,
3
14.15, 22.7, 26.6, 29.6, 32.0, 36.8, 102.5, 103.4, 106.4 and
130.9 422 resonances are missing); m/z 4FAB) 2209.5 4M1,
100%).
3.1.13. 5,10,15,20-Tetra-ꢀp-methoxyphenyl)porphyrin 17.
Borontri¯uoride etherate 40.1 mL) was added to a stirred
solution of pyrrole 43.3 g, 49 mmol) and p-methoxybenzal-
dehyde 46.6 g, 49 mmol) in CH2Cl2 4250 mL) under argon.
Stirring was continued for 44 h and DDQ 48.3 g, 37 mmol)
added. Stirring was continued for 10 min more. The solvent
was removed under reduced pressure and the residue
dissolved in CHCl3 before ®ltration. The insoluble product
was washed with CHCl3 to give the title compound 41.7 g,
27%) as a mauve solid, mp.2508C; lmax4CHCl3)/nm 422
4log e 5.8); nmax 4KBr)/cm21 3311w, 2955w, 2928w,
2899w, 2832w, 1604m, 1552w, 1506s, 1464m, 1404w,
1348m, 1288m, 1246vs, 1173s, 1104m, 1071m, 1032s,
985w, 961m, 840w, 802s, 736m and 638w; dH 4250 MHz;
CDCl3) 22.76 42H, s, N±H);4.09 412H, s, OMe), 7.28 48H,
d, Jˆ8.5 Hz), 8.11 48H, d, Jˆ8.5 Hz) and 8.85 48H, s,
b-pyrrolic); dC 462.9 MHz;CDCl 3) 55.6, 112.2, 119.8,
131.0, 134.7, 135.6 and 159.4 41 resonance is missing);
m/z 4FAB) 735.2958 4M11H. C48H39N4O4 requires
735.2958), 735.2 4M11H, 100%).
462.9 MHz;CDCl ) 95.3, 97.6, 99.7, 121.6, 124.0, 124.2,
3
130.0, 130.2, 130.6, 132.1, 132.3, 132.4, 132.7, 140.0,
140.1, 147.0 and 149.3 4one resonance is missing); m/z
1
4FAB) 977 4M1, 100%);4EI) 976.4676 4M C64H60N6O4
requires 976.4672).
3.1.11. 5,10,15,20-tetrakis-Triisopropylsilylethynylpor-
phyrin 14. Borontri¯uoride etherate 41.1 mL) was added
to a stirred solution of pyrrole 43.80 g, 10 mmol) and 3-
triisopropylsilylprop-2-ynal
2
411.95 g, 10 mmol) in
CH2Cl2 45 L), cooled to 2788C. The solution was allowed
to warm to rt over 2 h. Stirring was continued for a further
1 h, DDQ 49.7 g, 7.5 mmol) was added, stirring continued
for 10 min and the solution ®ltered through silica. The
solvent was removed under reduced pressure and the resi-
due, dissolved in light petroleum/CH2Cl2 41:1), ®ltered
through silica. The solvent was removed under reduced
pressure and the residue was crystallised form CH2Cl2/
MeOH to give the title compound 43.96 g, 27%) as a purple
solid with a metallic lustre, mp.2508C;4Found: C, 74.7;H,
9.1;N, 5.6. C 64H94N4Si4 requires C, 74.5;H, 9.2;N, 5.4%);
3.1.14. [5,15-Bis-ꢀ3,5-bis-tert-butylphenyl)-10,20-bis-tri-
isopropylsilylethynylporphinato]zincꢀII) 18. Method 1.
A suspension of porphyrin 9 440 mg, 0.04 mmol) and
Zn4OAc)2´2H2O 4670 mg, 3 mmol) in DMF 415 mL) was
re¯uxed for 1 h, under argon. The resulting deep green solu-
tion was poured into water 450 mL). The precipitate was
®ltered and washed with water, MeOH and recrystallised
from CH2Cl2/MeOH to give the title compound 441 mg,
98%) as a purple crystalline solid. Method 2. A solution
of lithium bis-trimethylsilylamide 41.2 mL, 1 M in THF,
1.2 mmol) was added to a rapidly stirred solution of
[10,20-bis-43,5-bis-tert-butylphenyl)-5,15-bis-ethynylpor-
phinato]zinc4II) 229,12 40.5 g, 0.6 mmol) in dry THF
4pyridine 1%) 460 mL) under an argon atmosphere. After
10 min chlorotriisopropylsilane 40.27 mL, 1.2 mmol) was
added. Stirring was continued for 30 min, aqueous
potassium hydroxide 41 M, 30 mL) was added and the solu-
tion poured into CHCl3. The solution was washed with
water and the organic layer dried over MgSO4. The solvent
was removed under reduced pressure and the residue
washed with MeOH. The residue was crystallised from
l
max4CHCl3)/nm 450 4log e 5.7), 607 44.9) and 710 44.3);
nmax 4KBr)/cm21 457m, 572m, 669s, 705vs, 794m, 877m,
914w, 987m, 1058w, 1132m, 1238m, 1342w, 1459s,
1502w, 1616w, 2136s, 2356w, 2858s, 2942s, 3407m,
3478m and 3544m; dH 4250 MHz;CDCl ) 21.76 42H, s,
3
N±H), 1.44 and 1.46 484H, m, i-Pr), 9.55 48H, s, b-pyrrolic);
dC 462.9 MHz;CDCl ) 11.9, 19.1, 100.3, 102.6 and 107.7
3
4two resonances are missing); m/z 4FAB) 1031.8 4M1, 100%).
3.1.12. 5,10,15,20-tetrakis-[Dimethyl-ꢀ2-dodecylhexa-
decyl)-silylethynyl]porphyrin 15. Borontri¯uoride etherate

2420
M. J. Plater et al. / Tetrahedron 58 12002) 2415±2422
CH2Cl2/MeOH to give the title compound 40.55 g, 79%),
mp.2508C 4dichloromethane/methanol). lmax4CHCl3)/nm
438 4log e 5.7), 449 45.5) and 637 44.7); nmax 4KBr)/cm21
2956vs, 2863s, 2138m, 1591m, 1498m, 1462m, 1362m,
1288m, 1246m, 1212m, 1163m, 1063m, 1005m, 929m,
881m, 825w, 797m, 721s, 675m, 620w and 507w; dH
4250 MHz;CDCl 3) 1.46 442H, m, i-Pr), 1.57 436H, s,
t-Bu), 7.83 42H, t, Jˆ2 Hz, p-Ph), 8.05 44H, d, Jˆ2 Hz,
o-Ph), 9.00 44H, d, Jˆ5 Hz) and 9.78 44H, d, Jˆ5 Hz); dC
462.9 MHz;CDCl 3) 11.9, 19.2, 31.8, 35.1, 98.5, 101.7,
109.3, 121.2, 124.1, 129.3, 131.2, 133.2, 141.2, 148.8,
150.5 and 152.4; m/z 4FAB) 1108.6139 4M1 C70H92N4Si2Zn
requires 1108.6152), 1108.6 4M1, 100%).
on silica with light petroleum 60±80/THF 43:1) as eluent.
The ®rst fraction was collected and the solvent removed
under reduced pressure. The residue was recrystallised
from CH2Cl2/MeOH and dried under vacuum to give the
title compound 4470 mg, 73%) as a purple crystalline
solid, mp.2508C 4dichloromethane/methanol) 4Found: C,
81.1;H, 6.2;N, 5.6. C 64H62N4Zn requires C, 80.7;H, 6.6;
N, 5.9%);4 lmax4CHCl3)/nm 447 4log e 5.6) and 651 44.7);
nmax 4KBr)/cm21 2956vs, 2904s, 2865s, 1591s, 1499s,
1473m, 1423w, 1362m, 1286m, 1246m, 1208s, 1062w,
1005m, 933w, 791m, 749m, 710m and 685m; dH
4250 MHz;CDCl ) 1.57 436H, s, t-Bu), 7.52 46H, m), 7.84
3
42H, t, Jˆ1.8 Hz, p-Ph), 8.01 44H, m), 8.09 44H, d,
Jˆ1.8 Hz, o-Ph), 9.00 44H, d, Jˆ4.6 Hz) and 9.77 44H, d,
3.1.15. [5,15-Bis-ꢀ3,5-bis-tert-butylphenyl)-10,20-bis-tri-
isopropylsilylethynylporphinato]copperꢀII) 19. A sus-
Jˆ4.6 Hz); dC 462.9 MHz;CDCl ) 31.8, 35.1, 92.5, 96.7,
3
101.6, 121.1, 124.2, 124.3, 128.5, 128.7, 129.8, 130.9,
131.7, 133.1, 141.2, 148.8, 150.5 and 152.0; m/z 4FAB)
950.4 4M1, 100%).
pension of porphyrin
9
440 g, 0.04 mmol) and
Cu4OAc)2´H2O 4650 mg, 3 mmol) in DMF 420 mL) was
re¯uxed for 4 h under argon. The resulting green solution
was poured into water and extracted with CH2Cl2. The
solution was dried over MgSO4 and the solvent removed
under reduced pressure to leave a green oil. MeOH was
added and the precipitate ®ltered to give the title compound
410 mg, 24%) as a green powder, mp.2508C; lmax4CHCl3)/
nm 432 4log e 5.8) and 609 44.6); nmax 4KBr)/cm21 2960vs,
2863m, 2144m, 1592m, 1520w, 1460m, 1346w, 1293w,
1260m, 1214m, 1167w, 1069m, 1010m, 928w, 881w,
799m, 723m and 676w; m/z 4FAB) 1107.6129 4M1.
C70H92N4Si2Cu requires 1107.6157), 1107.6 4M1, 100%).
3.1.18.
phenylethynylporphinato]leadꢀII) 23. Method 1.
[5,15-Bis-ꢀ3,5-bis-tert-butylphenyl)-10,20-bis-
A
suspension of porphyrin 11 420 mg, 0.023 mmol) and
Pb4OAc)2´3H2O 41.0 g, 2.6 mmol) in DMF 420 mL) was
re¯uxed for 2 h. The resultant solution was poured into
water and ®ltered to give the title compound 424 mg,
98%) as a deep green solid. Method 2. A solution of
porphyrin 11 4195 mg, 0.22 mmol) in THF/MeOH
420 mL, 1:1) and Pb4OAc)2´3H2O 41 g, 2.6 mmol) was
re¯uxed for 4 h and allowed to cool. Water was added and
the mixture extracted with Et2O 43£20 mL). The ethereal
layer was dried over MgSO4 and MeOH 430 mL) added. The
solvent was reduced to a small volume and the precipitate
®ltered. The residue was recrystallised from CH2Cl2/MeOH
to give the title compound 4190 mg, 79%) as a deep green
solid, mp.3008C; lmax4CH2Cl2)/nm 477 4log e 5.4), 497
45.3) and 720 44.8); nmax 4KBr)/cm21 620m, 794m, 923m,
997w, 1203m, 1245m, 1475m, 1589m, 1616m, 2954m,
3413vs, 3475s and 3552s; dH 4250 MHz;CDCl 3) 1.52
418H, s, t-Bu), 1.60 418H, s, t-Bu), 7.54 46H, m), 7.83
42H, t, Jˆ1.8 Hz, p-Ph), 7.91 42H, bs, o-Ph), 8.03 44H,
m), 8.21 42H, bs, o-Ph), 9.00 44H, d, Jˆ4.6 Hz) and 9.81
44H, d, Jˆ4.6 Hz); dC 462.9 MHz;CDCl 3) 31.8, 35.1, 96.7,
102.4, 121.11, 124.3, 125.9, 128.5, 128.7, 129.6, 130.6,
130.9, 131.7, 133.2, 141.3, 148.7, 148.9, 149.3 and 151.1;
m/z 4FAB) 1093.4668 4M11H. C64H61N4Pb requires
1093.4662), 1092.3 4M1, 25%) and 887.4 4M12Pb12H,
100).
3.1.16. [5,15-Bis-ꢀ3,5-bis-tert-butylphenyl)-10,20-bis-tri-
isopropylsilylethynylporphinato] leadꢀII) 20. A suspen-
sion of porphyrin
9
440 mg, 0.04 mmol) and
Pb4OAc)2´3H2O 41.2 g, 3 mmol) in DMF 420 mL) was
re¯uxed for 4 h under argon. The resulting deep green solu-
tion was poured into water 450 mL). The precipitate was
®ltered, washed with water, MeOH and recrystallised
from CH2Cl2/MeOH to give the title compound 430 mg,
63%) as a deep green, almost black, solid, mp.3008C
4dichloromethane/methanol) 4Found: C, 67.9;H, 7.5;N,
4.35. C70H92N4PbSi2 requires C, 67.1;H, 7.4;N, 4.5%);
l
max4CHCl3)/nm 473 4log e 5.3), 493 45.3) and 704 44.6);
nmax 4KBr)/cm21 2955vs, 2862s, 2361w, 2332w, 2134m,
1589m, 1470m, 1389w, 1361m, 1280m, 1244m, 1207s,
1157m, 1062w, 995m, 923m, 880m, 794m, 717vs, 670m
and 565w; dH 4400 MHz;CDCl ) 1.55 478H, m, t-Bu and
3
i-Pr), 7.82 42H, t, Jˆ2 Hz, p-Ph), 7.87 42H, bs, o-Ph), 8.19
42H, bs, o-Ph), 8.99 44H, d, Jˆ4 Hz) and 9.78 44H, d,
Jˆ4 Hz); dC 4100.6 MHz;CDCl ) 13.0, 20.2, 32.8, 36.0,
3.1.19. [5,15-Bis-ꢀ3,5-di-tert-butylphenyl)-10,20-bis-ꢀp-
nitrophenylethynyl)porphinato]leadꢀII) 24. A mixture of
porphyrin 12 4100 mg, 0.1 mmol) and Pb4OAc)2´3H2O
40.5 g, 1.3 mmol) in DMF was re¯uxed for 2 h. The solution
was poured into water, ®ltered and the residue washed with
water. The residue was dissolved in THF, ®ltered, the
solvent removed under reduced pressure and the residue
washed with MeOH to give the title compound 4110 mg,
90%) as a brown solid, mp.2508C; lmax4CHCl3)/nm 485
4log e 5.3) and 739 44.9); nmax 4KBr)/cm21 709m, 786s,
844s, 927m, 993w, 1099m, 1199s, 1243s, 1328vs, 1423m,
1479s, 1508s, 1583s, 2181vs, 2861m and 2948vs; dH
3
99.5, 103.4, 110.7, 122.2, 126.6, 131.0, 132.0, 134.2,
142.3, 150.3 and 152.5 42 resonances are missing); m/z
4FAB) 1252.6623 4M1. C70H92N4Si2Pb requires
1252.6627), 1252.7 4M1, 100%).
3.1.17.
[5,15-Bis-ꢀ3,5-bis-tert-butylphenyl)-10,20-bis-
phenylethynylporphinato]zincꢀII) 21. Et3N 44 mL
distilled from CaH2) was added to a stirred solution of
[10,20-bis-43,5-bis-tert-butylphenyl)-5,15-bis-ethynylpor-
phinato]zinc4II) 22 4510 mg, 0.64 mmol), iodobenzene
4750 mg, 3.7 mmol), Pd4PPh3)2Cl2 410 mg, 14 mmol) and
CuI 410 mg, 52 mmol) in THF 440 mL) under argon. Stirring
was continued for 16 h before the solvent was removed
under reduced pressure. The residue was chromatographed
4250 MHz;CDCl ) 1.54 and 1.60 42£18H, s, t-Bu), 7.86
3
42H, bs), 7.93 42H, bs), 8.03 44H, d, Jˆ8.6 Hz), 8.22 42H,
bs), 8.31 44H, d, Jˆ8.6 Hz), 9.04 44H, d, Jˆ4.6 Hz) and

M. J. Plater et al. / Tetrahedron 58 12002) 2415±2422
2421
9.76 44H, d, Jˆ4.6 Hz); dC 462.9 MHz;CDCl ) 31.8, 35.1,
with THF, ®ltered and the solvent removed under reduced
pressure to give the title compound 4320 mg, 60%) as a dark
purple solid, mp.2508C; lmax4CHCl3)/nm 353 4log e 4.8),
465 45.6) and 656 44.3); nmax 4KBr)/cm21 3051w, 3018w,
1803w, 1593m, 1512m, 1472m, 1437m, 1324m, 1198m,
1176w, 1070m, 1004m, 982vs, 792s, 750s, 704s and
3
95.1, 98.7, 101.2, 121.4, 124.0, 126.8, 129.6, 130.6, 130.8,
130.9, 132.0, 133.7, 140.9, 146.9, 148.9, 149.1, 149.7 and
151.2 42 resonances are missing); m/z 4FAB) 1182.9 4M1,
100%).
3.1.20. [5,10,15,20-tetrakis-Triisopropylsilylethynylpor-
phinato]zincꢀII) 25. A mixture of porphyrin 14 40.71 g,
0.7 mmol) and Zn4OAc)2´2H2O 41 g, 4.6 mmol) in DMF
460 mL) was heated at re¯ux. After 1 h water was added
and the precipitate ®ltered, washed with water, MeOH and
recrystallised from CH2Cl2/MeOH to give the title
compound 40.71 g, 95%) as a purple solid, mp.2508C;
4Found: C, 70.8;H, 8.5;N, 4.8. C 64H92N4Si4Zn requires
659w; dH 4250 MHz;CDCl ) 7.76 412H, m), 8.10 48H,
3
bm) and 8.95 48H, s, b-pyrrolic); dC 462.9 MHz;CDCl )
3
122.32, 126.47, 127.48, 132.03, 134.71, 143.03 and
149.32; m/z 4FAB) 821.2157 4M11H. C44H29N4Pb requires
821.2158), 820.2 4M1, 28%).
3.1.24. [5,10,15,20-Tetra-ꢀp-methoxyphenyl)-porphin-
ato]leadꢀII) 29. A suspension of porphyrin 17 4190 mg,
0.26 mmol) and Pb4OAc)2´3H2O 42.0 g, 5 mmol) in DMF
440 mL) was re¯uxed for 24 h. The resulting solution was
poured into water and ®ltered. The residue was dissolved in
THF, ®ltered and the solvent removed under reduced
pressure to give the title compound 4157 mg, 65%) as a
mauve powder, mp.2508C; lmax4CHCl3/pyridine 41%))/
nm 468 4log e 5.2) and 766 44.8); nmax 4KBr)/cm21
3470w, 3424w, 2997w, 2950w, 2900w, 2830w, 1601m,
1508vs, 1463s, 1405m, 1323m 1285m, 1243vs, 1172s,
1105w, 1030m, 982s, 843w, 796s, 751m, 719w and 634w;
C, 70.2;H, 8.5;N, 5.1%);
lmax4CHCl3)/nm 463 4log e
5.7) and 656 44.4); nmax 4KBr)/cm21 2937vs, 2860vs,
2137s, 1496m, 1459s, 1381w, 1336w, 1212m, 1158s,
1062m, 1003m, 879m, 792m, 714vs, 669s, 577m and
459w; dH 4250 MHz;CDCl ) 1.51 and 1.53 484H, m, i-Pr)
3
and 9.62 48H, s, b-pyrrolic); dC 462.9 MHz;CDCl ) 11.9,
3
19.2, 99.2, 103.1, 108.6, 131.9 and 152.3; m/z 4FAB) 1094.7
4M1, 100%).
3.1.21. [5,10,15,20-tetrakis-Triisopropylsilylethynylpor-
phinato]leadꢀII) 26. A mixture of porphyrin 14 40.71 g,
0.5 mmol) and Pb4OAc)2´3H2O 42 g, 5 mmol) in DMF
460 mL) was heated at re¯ux. After 2 h water was added
and the precipitate ®ltered, washed with water, MeOH and
recrystallised from CH2Cl2/MeOH to give the title
compound 40.54 g, 90%) as a green solid, mp.2508C;
4Found: C, 62.0;H, 7.4;N, 4.4. C 64H92N4Si4Pb requires C,
62.1;H, 7.5;N, 4.5%); lmax4CHCl3)/nm 500 4log e 5.8) and
719 44.9); nmax 4KBr)/cm21 457m, 516w, 572m, 665s,
709vs, 788m, 877m, 993m, 1058m, 1149s, 1203m,
1238w, 1315w, 1380w, 1463s, 2130s, 2858s, 2935s,
dH 4250 MHz;CDCl ) 4.10 412H, s, O±Me), 7.28 48H, d,
3
Jˆ5.2 Hz, Ph), 8.12 48H, bd, Jˆ5.2 Hz, Ph) and 8.97 48H, s,
b-pyrrolic); dC 462.9 MHz;CDCl 3) 55.6, 112.0, 121.8,
131.9, 135.5, 135.7, 149.6 and 159.2; m/z 4FAB) 941.2590
4M11H. C48H36N4O4Pb requires 941.2581), 940 4M1, 6%)
and 735 4M1Pb, 100).
Acknowledgements
We are grateful to the EPSRC national mass spectrometry
service center for mass spectra.
3408m, 3476m and 3547w; dH 4250 MHz;CDCl ) 1.50
3
and 1.51 484H, m, i-Pr) and 9.67 48H, s, b-pyrrolic); dC
462.9 MHz;CDCl ) 12.0, 19.3, 99.3, 104.1, 108.7, 131.9
3
and 151.2; m/z 4FAB) 1236.2 4[M1H]1, 100%).
References
3.1.22. [5,10,15,20-tetrakis-[Dimethyl-ꢀ2-dodecylhexade-
cyl)-silylethynyl]porphinato]leadꢀII) 27. A solution of
porphyrin 15 4100 mg, 0.045 mmol) and Pb4OAc)2´3H2O
40.5 g, 1.3 mmol) in CH2Cl2/MeOH 4100 mL, 4:6) was
re¯uxed for 4 h. Water was added and the solution extracted
with CH2Cl2 42£50 mL). The solvent was removed under
reduced pressure and the residue puri®ed by thin layer chro-
matography. Elution with light petroleum/CH2Cl2 425:1)
gave the title compound 4108 mg, 99% as a deep green
amorphous solid, lmax4CHCl3)/nm 500 4log e 5.8) and 719
44.9); dH 4250 MHz;CDCl 3) 0.24 48H, d, Jˆ7.6 Hz,
Si±CH2), 0.64 424H, s, Si±Me), 0.87 424H, m, Me), 1.28
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6. 4a) Kruithof, K. J. H.;Schmitz, R. F.;Klumpp, G. W.
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107.3, 132.0 and 151.3 415 resonances are missing); m/z
4FAB) 2415.7 4M1, 100%).
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0.65 mmol) and Pb4OAc)2´3H2O 48.0 g, 21 mmol) in DMF
4120 mL) was re¯uxed for 36 h. The resulting solution was
poured into water and ®ltered. The residue was extracted
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11538±11545.

2422
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