Synthesis and characterisation of N-1,10-phenanthrolin-5-ylalkylamides and their photosensitising heteroleptic Ru(II) complexes

Article abstract of DOI:10.1016/j.tet.2005.08.012

In the context of our studies on ruthenium(II) complexes containing polyazaheterocyclic ligands as functionalised photosensitisers for singlet molecular oxygen generation in heterogeneous phase, we describe the synthesis and spectroscopic characterisation of different amide-functionalised N-1,10-phenanthrolin-5-ylalkylamides. These chelators are used to obtain heteroleptic [Ru(phen)₂L²⁺ complexes, where L stands for 2-iodo-N-1,10-phenanthrolin-5-ylacetamide (5-iap), 4-oxo-4-(1,10-phenanthrolin- 5-ylamino)butanoic acid (5-suap), 5-oxo-5-(1,10-phenanthrolin-5-ylamino) pentanoic acid (5-glap) and tert-butyl 4-oxo-4-(1,10-phenanthrolin-5-ylamino) butylcarbamate (BOC-5-ngap). The spectroscopic data, excited state lifetimes and quenching rate constants with O₂ (ca. 3.7 × 10⁹ L mol^-1 s^-1) of these novel complexes are also reported.

Full text of DOI:10.1016/j.tet.2005.08.012

Tetrahedron 61 (2005) 9478–9483
Synthesis and characterisation of N-1,10-phenanthrolin-5-
ylalkylamides and their photosensitising heteroleptic
Ru(II) complexes
*
´
Pedro Ramiro, David Garcıa-Fresnadillo and Guillermo Orellana
Laboratory of Applied Photochemistry, Department of Organic Chemistry, Faculty of Chemistry, Universidad Complutense de Madrid,
E-28040 Madrid, Spain
Received 17 June 2005; revised 29 July 2005; accepted 2 August 2005
Available online 19 August 2005
Abstract—In the context of our studies on ruthenium(II) complexes containing polyazaheterocyclic ligands as functionalised
photosensitisers for singlet molecular oxygen generation in heterogeneous phase, we describe the synthesis and spectroscopic
characterisation of different amide-functionalised N-1,10-phenanthrolin-5-ylalkylamides. These chelators are used to obtain heteroleptic
[Ru(phen)2L]2C complexes, where L stands for 2-iodo-N-1,10-phenanthrolin-5-ylacetamide (5-iap), 4-oxo-4-(1,10-phenanthrolin-5-
ylamino)butanoic acid (5-suap), 5-oxo-5-(1,10-phenanthrolin-5-ylamino)pentanoic acid (5-glap) and tert-butyl 4-oxo-4-(1,10-phenan-
throlin-5-ylamino)butylcarbamate (BOC-5-ngap). The spectroscopic data, excited state lifetimes and quenching rate constants with O2
(ca. 3.7!109 L molK1 sK1) of these novel complexes are also reported.
q 2005 Elsevier Ltd. All rights reserved.
1. Introduction
reactive oxygen species, typically generated by electronic
energy transfer from the triplet excited state of certain dyes
(methylene blue, rose bengal, phenalenone, porphyrins,.),13
are useful for photosensitised oxidation of organic
compounds and fine chemicals synthesis,14,15 molecular
probing of microheterogeneous systems,16 as the ‘magic
bullet’ in photodynamic therapies (PDT)17 and water
disinfection.18,19 For both synthetic and disinfection
purposes, immobilisation of the photosensitising dye onto
a solid support allows an easy removal after fulfilling its
function.
Ruthenium(II) complexes with polyazaaromatic chelating
ligands have been widely studied because of their unique
spectroscopic, photochemical and redox properties.1,2 Since
1959, when the luminescence of tris(2,20-bipyridine)ruthe-
nium(II), [Ru(bpy)3]2C, was described for the first time,3
these structures have been used in many areas of chemistry,
such as photonic and optoelectronic devices,4 luminescent
probes for micelles and other organised media,5 artificial
photonucleases and photochemical reporters of the rich
DNA morphology,6 development of therapeutic agents,7
constituents of supramolecular edifices,8 chemiluminescent
analytical reagents9 and luminescent indicator dyes for
optochemical sensing,10 to name just a few.
The spectroscopic, photophysical and photochemical
features of Ru(II) polypyridyl complexes may be finely
tuned by a judicious molecular design of the heterocyclic
chelating ligands in the co-ordination sphere. Moreover,
introduction of different ligands around the metal centre (so-
called heteroleptic complexes) provides an even finer tuning
of their properties and allows introduction of suitable
chemical groups for covalent attachment to functionalised
solid supports.
The variety of applications for these complexes does not end
here: due to their microsecond excited state lifetimes and the
diffusion-controlled O2 quenching rate constants, they
display a high quantum yield of singlet (molecular) oxygen,
abbreviated O2(1Dg), production (FD).11,12 For instance, a
FD of 1.0 has been measured for tris(4,7-diphenyl-1,10-
phenanthroline)ruthenium(II) in methanol solution.12 Such
In this work, we describe the synthesis of a family of N-1,
10-phenanthrolin-5-ylalkylamide ligands (L) containing a
spacer and an electrophilic or nucleophilic end group to
tether the corresponding heteroleptic Ru(II) complex to
either organic or inorganic polymer supports bearing the
opposite chemical function. Phen (1,10-phenanthroline) has
Keywords: 1,10-Phenanthroline; Ruthenium(II) complexes; Polyazaheter-
ocyclic ligands; Singlet oxygen; Photosensitisers.
Corresponding author. Tel.: C34 913944220; fax: C34 913944103;
e-mail: orellana@quim.ucm.es
*
0040–4020/$ - see front matter q 2005 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tet.2005.08.012

P. Ramiro et al. / Tetrahedron 61 (2005) 9478–9483
9479
Table 1. Chemical yields of the synthesis of N-1,10-phenanthrolin-5-
ylalkylamides (1a–d) and their corresponding heteroleptic Ru(II)
complexes (2a–d)
been selected as the ancillary ligand to maximise the
emission lifetime and FD of the sensitising dye.11 Such
molecular engineering aims to impart the immobilised
[Ru(phen)2L]2C complex the widest compatibility with the
solvent (i.e., both aqueous and organic media) for water
treatment20 and synthetic purposes,14 and to serve as
oxygen-sensitive luminescent materials for optosensor
development.10,21,22
R
Ligand Yield (%) Complex Yield (%)
CH2I
1a
1b
1c
1d
96
25
43
42
2a
2b
2c
2d
55
36
47
46
(CH2)2CO2H
(CH2)3CO2H
(CH2)3NHCO2C(CH3)3
While some work on chemical derivatisation of 1,10-
phenanthrolin-5-amine (5-ap) has been reported for intro-
ducing long alkyl chains23 or biomolecular labelling,24–27 we
have developed general procedures for the (difficult)
acylation of 5-ap using carboxylic acid anhydrides. In this
way, the functionalised phen ligands 1 were prepared
(Scheme 1) and fully characterised by NMR, as well as their
corresponding heteroleptic Ru(II) complexes 2 (Scheme 2).
ligands in only one step. The usual low yields are related to
steric hindrance to the approach of the electrophile due to
the peri hydrogen atom in the 4-position. Actually, the
highest chemical yield is obtained with the smallest
carboxylic acid anhydride (iodoacetic), an improvement
over the literature procedure.24
Protection of the u-amino group with BOC is required to
avoid competition in the amide formation step of
phenanthroline 1d (Scheme 1). Facile deprotection of the
tert-butyloxycarbonyl moiety can be carried out with acetyl
chloride in methanol.30
Once the functionalised phenanthrolines are prepared, they
are used for the synthesis of heteroleptic ruthenium(II)
complexes. The reaction of cis-dichloro-bis-(1,10-phenan-
throline)ruthenium(II), Ru(phen)2Cl2, and the chelating
ligands (1a–d) in methanol affords the complexes (2a–d)
(Scheme 2) in moderate yields (36–55%) after repeated
precipitation as PFK6 salts (Table 1). The chemical
composition and structure of these novel complexes has
been confirmed by the usual spectroscopic methods (high-
field 1H and 13C NMR, electrospray ionisation MS and
elemental analysis).
Scheme 1. Conditions: (i) 1a: (ICH2CO)2O/CHCl3/D; (ii) 1b: (COCH2-
CH2CO)O/PTSA/CHCl3; (iii) 1c: (COCH2CH2CH2CO)O/PTSA/CHCl3;
(iv) 1d: (1) ClCO2Et/Et3N, (2) BOC-GABA-OH/CHCl3.
The 1H NMR signals are characteristic of the Ru(II)
polypyridyl complexes, taking into account the combined
effects on the chemical shifts of electronic s-donation to the
metal centre, p-back-bonding to the ligand and magnetic
anisotropy of the heterocyclic rings.31 The a,b and g
protons of the phenanthroline ring appear separately in the
aromatic region (dgOdaOdb).5 The CH2 singlet from the
amide side chain is duplicated in the case of 2a, and two
signals are observed in 7:3 area ratio. A similar pattern
appears in 2c, where two of the three methylene groups
display duplicate signals (3:2 area ratio). The NH proton is
also observed twice for 2a and 2c in the same ratio described
above. Duplication of some signals is observed also in the
13C NMR spectra of those Ru(II) complexes, especially
those corresponding to the carbonyl and the side chain
methylene groups. As no signal duplication is observed in
any of the free ligands, restricted rotation around the
C5phen–Namide bond could explain these experimental
facts. The strong electron-withdrawing character of the
metal complex increases the order of such single bond
due to enhanced mesomeric effect of the aminocarbonyl
group.
Scheme 2.
In addition to their structural characterisation, the absorp-
tion and luminescence spectra, the emission lifetimes and
the excited state quenching rate constants with dissolved
oxygen have been determined for the novel sensitisers in
acetonitrile solution. Proof of singlet oxygen generation in
this solvent, using its phosphorescence at 1270 nm, is
provided.
2. Results and discussion
The synthesis of the functionalised N-1,10-phenanthrolin-5-
ylalkylamides (1a–d) is carried out by the reaction between
1,10-phenanthrolin-5-amine and different anhydrides either
from commercial sources or prepared in situ, modifying
some methods described in the literature26,28,29 (Scheme 1).
This reaction takes place with moderate to excellent yields
(25–96%) (Table 1) and is a simple way to obtain such
The base peak in the ESI mass spectra of these complexes
corresponds to the [M]2C ion. In case of having a carboxylic
acid moiety on the side chain, the [MKH2O]2C ion is
observed instead. No abundant fragments are detected
together with the molecular ions.

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P. Ramiro et al. / Tetrahedron 61 (2005) 9478–9483
Spectroscopic and photophysical data of the novel Ru(II)
complexes (2a–d) have also been measured (Table 2). Their
absorption spectra display bands in two regions, an intense
one around 265 nm that may be ascribed to the ligand-
centred p–p* transition, and a maximum that corresponds
to the metal-to-ligand charge transfer (MLCT) d–p*
transition at approximately 450 nm. Regardless the absorp-
tion maximum, all the complexes show strong emission
peaking around 595 nm. Similar values have been reported
for the homoleptic tris-phenanthroline complex.2
The excited state lifetimes (t) of these novel photosensi-
tisers were measured in N2-saturated, air-equilibrated and
O2-purged acetonitrile solutions (Table 2). In the absence of
dioxygen, the emission lifetimes of the heteroleptic Ru(II)
complexes (2a–d) are ca. 700 ns, a value slightly lower than
that of [Ru(phen)3]2C. Therefore, introduction of the amide
group and functionalised side chain in the 5-position of the
phen ligand does not perturb significantly the electronic
features of the metal complex and provides a high efficiency
of excited state quenching by O2 (80% of the 3MLCT states
produced are deactivated by O2 in the air-equilibrated
solvent, Table 2). The sensitiser quenching rate constants
(kq) in acetonitrile can be determined from the observed
(linear) Stern–Volmer relationships (t0/tZ1Ckqt0[O2]).32
The calculated kq values (Table 2) are close to 4!
109 L molK1 sK1, a value near the diffusion control limit
at room temperature. These photochemical parameters also
make them highly suitable for luminescence oxygen sensing
with fibre-optic probes.10
Figure 1. Decay of the emission signal at 1270 nm after laser-flash
excitation of an air-equilibrated acetonitrile solution of photosensitising
complex 2d. The solid line through the experimental points represents the
best fit to the function I(t)Z0.02C0.0047 exp(Kt/4.1)C0.0148 exp(Kt/21).
Inset: emission spectrum recorded 2.5 ms after the laser pulse.
allow us to prepare solid-supported photosensitisers con-
taining the covalently bonded dye. Using easy straight-
forward synthetic procedures, we may attach the efficient
1O2 generators to activated organic and inorganic polymer
materials, such as polystyrene, silica gel or glass beads, for
1
water/air disinfection, O2-mediated photooxidation reac-
tions or chemical optosensors. These fields are currently
being explored in our laboratory.
Moreover, we have confirmed the production of singlet
(molecular) oxygen from the O2 quenching of the excited
state of the novel photosensitisers. Laser-flash illumination
in the visible of an aerated acetonitrile solution of any of the
Ru(II) complexes (2a–d) followed by time-resolved
detection at 1270 nm (the characteristic 1O2 phosphor-
escence maximum)13 affords the typical decay kinetics
and emission spectrum of O2 (Fig. 1, O2 generation by
2d as a representative member of the family). The emission
decay traces have to be fit to a biexponential function due to
interference from the wide luminescence band of the
photoexcited Ru(II) complex, which is not fully quenched
by O2 under air-saturated conditions.
4. Experimental
4.1. General
All reagents were commercial grade and were used as
received unless otherwise stated. 1,10-Phenanthrolin-5-
amine (5-ap) was obtained from 5-nitro-1,10-phenanthro-
line (Aldrich) as previously described by Nasielski-Hinkens
et al.33 Ru(phen)2Cl2 was prepared according to the
procedure reported by Sullivan et al.34
1
1
Melting points were measured with a Bibby-Sterilin
apparatus and are uncorrected. 1H NMR and 13C NMR
spectra were recorded at the UCM NMR Central Instru-
mentation Facilities on a Bruker AC-200 at 200 MHz for 1H
and 50 MHz for 13C, or on a Bruker AMX-500 at 500 MHz
for 1H and 125 MHz for 13C. CDCl3, CD3CN, MeOH-d4 and
3. Conclusions
The novel amido-functionalised Ru(II) complexes will
Table 2. Wavelengths of the absorption and emission maximums, 3MLCT excited state lifetimes, O2 quenching constants and fraction of triplets quenched by
O2 for the Ru(II) complexes (2a–d) in acetonitrile solution at 25 8C
kq!10K9
max
abs
(nm)a
max
em
(nm)a,b
POT
POT
Complex
l
l
t (N2)
(ns)c
t (air)
(ns)c
t(O2)
(ns)c
2
2
(L molK1 sK1 d
)
(air)e
(O2)e
2a
2b
2c
2d
263, 446
262, 446
263, 448
263, 447
596
594
593
593
716
645
629
696
142
144
138
139
33
33
31
31
3.6
3.6
3.8
3.8
0.80
0.78
0.78
0.80
0.95
0.95
0.95
0.96
a Estimated uncertaintyG1 nm.
b Uncorrected for the instrument response function.
c Estimated uncertaintyG3%.
d From the Stern–Volmer lifetime quenching plot (see text); estimated uncertaintyG4%.
e Calculated from the equation: POT Z1Kðt=t0Þ.
2

P. Ramiro et al. / Tetrahedron 61 (2005) 9478–9483
9481
DMSO-d6 (Cambridge Isotope Laboratories) were used as
solvents. The chemical shifts (dH and dC) are given from the
residual CHCl3 signal (7.26 and 77.0 ppm, respectively).
Coupling constants (J) are given in Hz. Electron impact (EI)
mass spectra were carried out on a HP 5989A quadrupole
instrument at 70 eV with a source temperature of 250 8C.
Electrospray ionisation (ESI) mass spectra were obtained on
a Bruker Esquire-LCe apparatus using 3500 V as ionisation
voltage, N2 as nebuliser gas and methanol as solvent. Both
instruments belong to the UCM MS Central Instrumentation
Facilities. TLC analyses and column chromatography were
performed on silica gel 60F254 plates (Merck) and on silica
gel 60 (Merck, 70–230 mesh), respectively.
118.93 (CH), 124.51, 124.86 (CHb), 128.84, 132.40 (C),
133.53 (CHg), 138.25 (C), 140.56 (CHg), 141.16 (C),
146.73, 149.48 (CHa), 168.21 (CO); m/z (EI, 70 eV): 363
(MC%, 3), 236 (MC%KI, 100), 196 (5-NH2phenC%CH, 83),
168 (NHCOCH2IC%, 83), 127 (IC%, 63). Anal. Calcd for
C14H10IN3O$CHCl3: C, 37.34; H, 2.30; N, 8.71%, found: C,
37.13; H, 2.57; N, 9.15%.
4.2.1.2. 4-Oxo-4-(1,10-phenanthrolin-5-ylamino)buta-
noic acid, 5-suap, 1b. Precipitation of the crude product
with methanol afforded 74 mg (25%) of a white solid, mp
188–190 8C (MeOH); dH (200 MHz, DMSO-d6): 2.62
(t, 2H, JZ6.2 Hz, CH2), 2.79 (t, 2H, JZ6.2 Hz, CH2),
7.74 (dd, 1Hb, JZ8.3, 4.3 Hz), 7.81 (dd, 1Hb, JZ8.3,
4.3 Hz), 8.43 (dd, 1Hg, JZ8.3, 1.5 Hz), 8.65 (dd, 1Hg, JZ
8.3, 1.5 Hz), 9.03 (dd, 1Ha, JZ4.3, 1.5 Hz), 9.12 (dd, 1Ha,
JZ4.3, 1.5 Hz), 10.22 (s, 1H, NH), 12.25 (br s, 1H, CO2H);
dC (50 MHz, DMSO-d6): 28.92, 30.63 (CH2), 119.93 (CH),
122.72, 123.49 (CHb), 124.69, 128.00 (C), 131.74 (CHg),
131.80 (C), 135.72 (CHg), 143.73, 145.74 (C), 149.23,
149.77 (CHa), 171.38 (CO2H), 173.87 (NHCO); m/z (EI,
70 eV): 295 (MC%, 6), 277 (MC%KH2O, 100), 249 (MC%K
HCO2H, 23), 195 (5-NH2phenC%, 46). Anal. Calcd for
C16H13N3O3$CH3OH: C, 62.38; H, 5.38; N, 12.84%, found:
C, 62.08; H, 5.63; N, 12.44%.
UV–vis absorption spectra were recorded with a Varian
Cary-3Bio spectrophotometer. Emission spectra were
obtained with a Perkin-Elmer LS-5 spectrofluorometer at
25 8C and are uncorrected for the instrumental response.
Emission lifetimes of the Ru(II) complexes were measured
with an Edinburgh Instruments LP-900 laser kinetic
spectrometer equipped with a frequency-doubled Nd:YAG
laser (Minilite II, Continuum, USA) for excitation at
532 nm (15 mJ per 3 ns pulse) and a red-sensitive
Hamamatsu R-928 photomultiplier. Decay traces were
recorded at 595 nm through a 550 nm cut-off filter with a
Tektronix TDS 340A digital oscilloscope, in N2-saturated,
air-equilibrated and O2-purged photosensitiser solutions in
4.2.1.3. 5-Oxo-5-(1,10-phenanthrolin-5-ylamino)pen-
tanoic acid, 5-glap, 1c. Filtration of reaction mixture
afforded 133 mg (43%) of a white solid, mp 233–235 8C
(CHCl3); dH (200 MHz, DMSO-d6): 1.92 (q, 2H, JZ7.3 Hz,
CH2), 2.38 (t, 2H, JZ7.3 Hz, CH2), 2.60 (t, 2H, JZ7.3 Hz,
CH2), 7.75 (dd, 1Hb, JZ8.3, 4.1 Hz), 7.83 (dd, 1Hb, JZ8.3,
4.1 Hz), 8.19 (s, 1H), 8.46 (dd, 1Hg, JZ8.3, 1.6 Hz), 8.62
(dd, 1Hg, JZ8.3, 1.6 Hz), 9.04 (dd, 1Ha, JZ4.1, 1.6 Hz),
9.14 (dd, 1Ha, JZ4.1, 1.6 Hz), 10.14 (s, 1H, NH), 12.15 (br
s, 1H, COOH); dC (50 MHz, DMSO-d6): 20.52, 33.05, 34.98
(CH2), 119.85 (CH), 122.83, 123.54 (CHb), 124.63, 128.10
(C), 131.83, 136.06 (CHg), 143.20, 145.34 (C), 148.91,
149.65 (CHa), 171.96 (CO2H), 174.15 (NHCO); m/z
(ESI)Z332 [MCNa]C, 310 [MCH]C. Anal. Calcd for
C17H15N3O3$CHCl3: C, 50.43; H, 3.76; N, 9.80%, found: C,
50.38; H, 4.06; N, 10.04%.
˚
spectroscopic-grade acetonitrile dried over 3 A molecular
sieves for more than one week. Measurements were carried
out after purging the solution with the corresponding gas for
at least 30 min. After transmission to a PII computer, the
kinetic parameters were extracted by exponential non-linear
least squares fitting to the experimental data using the
original EI software. 1O2 phosphorescence decay traces
were recorded at 1270 nm with an Edinburgh Instruments
EI-P N2-cooled fast Ge diode.
4.2. Preparation of N-1,10-phenanthrolin-5-ylalkyla-
mides, 1
4.2.1. Synthesis of phenanthrolines 1a, 1b and 1c. A
mixture of 1,10-phenanthrolin-5-amine (195 mg, 1 mmol)
and the corresponding anhydride (iodoacetic anhydride:
425 mg, 1.2 mmol; succinic anhydride: 500 mg, 5 mmol;
glutaric anhydride: 685 mg, 6 mmol, for 1a, 1b and 1c,
respectively), was dissolved in 30 mL of anhydrous CHCl3
at room temperature under argon. In the case of
phenanthrolines 1b and 1c, p-toluensulfonic acid (PTSA,
38 mg, 0.2 mmol) was also added as catalyst.
4.2.2. Synthesis of phenanthroline 1d. 1,10-Phenanthrolin-
5-amine (195 mg, 1 mmol) was dissolved in 30 mL of
CHCl3 and cooled at 0 8C under argon with an ice-water
bath. Triethylamine (405 mg, 4 mmol) and ethyl chloro-
formate (434 mg, 4 mmol) were then added and the reaction
mixture was stirred at this temperature for 30 min. Then,
4-(tert-butyloxycarbonylamino)butyric acid (BOC-GABA-
OH, 406 mg, 2 mmol) was added. The mixture was allowed
to reach room temperature and refluxed for 4 days. The
reaction progress was monitored by TLC.
After refluxing the reaction mixture for 2–3 days, an
insoluble precipitate was observed. It was filtered, washed
with chloroform and dried. Finally, the product was
recristallised in the appropriate solvent.
4.2.1.1. 2-Iodo-N-1,10-phenanthrolin-5-ylacetamide,
5-iap, 1a. Filtration of reaction mixture afforded 349 mg
(96%) of a yellow solid, mp 180 8C (with decomposition)
(CHCl3); dH (200 MHz, DMSO-d6): 4.10 (s, 2H, CH2), 8.06
(dd, 1Hb, JZ8.2, 4.2 Hz), 8.10 (dd, 1Hb, JZ8.2, 4.2 Hz),
8.42 (s, 1H), 8.88 (d, 1Hg, JZ8.2 Hz), 8.91 (d, 1Hg, JZ
8.2 Hz), 9.16 (d, 1Ha, JZ4.2 Hz), 9.27 (d, 1Ha, JZ4.2 Hz),
10.73 (s, 1H, NH); dC (50 MHz, DMSO-d6): 0.92 (CH2),
The reaction mixture was treated with an aqueous HCl (pH
4) solution (2!25 mL), the organic layer was separated and
washed successively with water (2!25 mL), Na2CO3-
saturated aqueous solution (2!25 mL) and water (2!
25 mL). Finally, it was dried over MgSO4. The solvent was
evaporated and the residue was purified by column
chromatography using dichloromethane/acetone 1:2 (v/v)
as the eluent.

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P. Ramiro et al. / Tetrahedron 61 (2005) 9478–9483
4.2.2.1. tert-Butyl 4-oxo-4-(1,10-phenanthrolin-5-
7.69 (m, 5Hb), 7.96 (d, 1Ha, JZ5.0 Hz), 8.02–8.08 (m,
5Ha), 8.27 (s, 4H), 8.55 (d, 1Hg, JZ8.3 Hz), 8.61–8.63 (m,
4Hg, 1H), 8.73 (d, 1Hg, JZ8.3 Hz), 8.97 (s, 1H, NH); dC
(125 MHz, CD3CN): 29.14, 30.30 (CH2), 119.70 (C),
125.68, 126.29, 126.36 (CH), 127.24 (C), 128.44 (CH),
131.19, 131.40, 131.42 (C), 132.63 (CH), 134.29 (C),
136.65, 137.18 (CH), 137.26, 146.18, 148.31, 148.34,
148.75 (C), 152.35, 153.32, 153.43, 153.47 (CH), 172.15
(CO), 173.63 (CO); m/z (ESI) Z369.5 [MKH2O]2C. Anal.
Calcd for [C40H29N7O3Ru](PF6)2: C, 45.90; H, 2.79; N,
9.37%, found: C, 45.54; H, 2.57; N, 9.23%.
ylamino)butylcarbamate, BOC-5-ngap, 1d. Purification
of the crude product by column chromatography afforded
160 mg (42%) of a yellow oil; dH (500 MHz, CDCl3): 1.51
(s, 9H, 3CH3), 2.00 (m, 2H, CH2), 2.71 (t, 2H, JZ6.4 Hz,
CH2), 3.36 (c, 2H, JZ6.2 Hz, CH2), 5.20 (t, 1H, JZ6.2 Hz,
NH), 7.58 (dd, 1Hb, JZ8.2, 4.2 Hz), 7.67 (dd, 1Hb, JZ8.2,
4.2 Hz), 8.26 (dd, 1Hg, JZ8.2, 0.9 Hz), 8.45 (s, 1H), 8.89
(dd, 1Hg, JZ8.2, 0.9 Hz), 9.00 (dd, 1Ha, JZ4.2, 0.9 Hz),
9.10 (dd, 1Ha, JZ4.2, 0.9 Hz), 10.31 (s, 1H, NH); dC
(50 MHz, CDCl3): 26.57 (CH2), 28.07 (CH3), 33.87, 39.33
(CH2), 79.21 (CMe3), 119.39 (CH), 122.17, 122.91 (CHb),
124.21, 127.82, 130.87 (C), 131.06, 135.51 (CHg), 143.38,
145.39 (C), 148.74, 149.15 (CHa), 156.81 (NHCO2), 172.98
(NHCO); m/z (EI, 70 eV) Z380 (MC%, 6), 324 ([MC%CH]–
4.3.3. [Bis(1,10-phenanthroline)(5-oxo-5-(1,10-phenan-
throlin-5-ylamino)pentanoic acid)]ruthenium(II) bis
(hexafluorophosphate), [Ru(phen)2(5-glap)](PF6)2, 2c.
Filtration of the product afforded 197 mg (47%) of a dark
orange solid; dH (500 MHz, CD3CN): 2.06 (q, 2H, JZ
7.3 Hz, CH2), 2.47 (t, 0.6H, JZ7.3 Hz, CH2), 2.50 (t, 0.4H,
JZ7.3 Hz, CH2), 2.68 (t, 0.6H, JZ7.3 Hz, CH2), 2.69 (t,
0.4H, JZ7.3 Hz, CH2), 7.59 (dd, 1Hb, JZ8.3, 5.2 Hz),
7.62–7.68 (m, 5Hb), 7.96 (d, 1Ha, JZ5.2 Hz), 8.02–8.09
(m, 5Ha), 8.28 (s, 4H), 8.54 (d, 1Hg, JZ8.3 Hz), 8.61–8.64
(m, 4Hg, 1H), 8.74 (d, 1Hg, JZ8.3 Hz), 8.95 (s, 0.6H, NH),
8.97 (s, 0.4H, NH); dC (125 MHz, CD3CN): 20.84, 20.90
(CH2), 32.98, 33.24 (CH2), 35.99, 36.02 (CH2), 119.86,
125.81, 126.34, 126.37 (CH), 126.45, 127.28 (C), 128.49
(CH), 131.18, 131.43, 131.44 (C), 132.89, 132.92 (CH),
134.34 (C), 136.64, 137.25 (CH), 146.15, 148.29, 148.33,
148.37, 148.71, 148.75, 152.32 (C), 152.36, 153.36, 153.40,
153.44, 153.49, 153.52 (CH), 172.86, 172.93 (CO), 173.87,
174.25 (CO); m/z (ESI) Z376.5 [MKH2O]2C. Anal. Calcd
for [C41H31N7O3Ru](PF6)2: C, 46.42; H, 2.95; N, 9.24%,
found: C, 46.17; H, 3.23; N, 9.10%.
C(CH3)3, 12), 307 (MC%KOC(CH3)3, 5), 195(5-NH2phenC%
,
100). Anal. Calcd for C21H24N4O3: C, 66.30; H, 6.36;
N,14.73%, found: C, 65.96; H, 6.31; N, 15.02%.
4.3. Preparation of [bis(1,10-phenanthroline)
(N-1,10-phenanthrolin-5-ylalkylamide)]ruthenium(II)
complexes, [Ru(phen)2(5-(N-COR)phen)](PF6)2, 2:
general procedure
A mixture of the corresponding N-1,10-phenanthrolin-5-
ylalkylamide 1 (0.450 mmol) and cis-dichloro-bis(1,10-
phenanthroline)ruthenium(II), Ru(phen)2Cl2 (200 mg,
0.375 mmol), was dissolved in 30 mL of methanol at
room temperature under argon atmosphere. The reaction
mixture was refluxed with stirring during 1–2 days. The
evolution of the reaction was monitored by TLC. Then the
mixture was concentrated at reduced pressure and 1 mL of a
saturated ammonium hexafluorophosphate (Fluka) aqueous
solution was added. Water was subsequently added to
favour precipitation of the product, which was then filtered
and washed with plenty of water. The complex was
reprecipitated from a methanol/water mixture and finally
dried under vacuum (40 8C, 0.1 Torr).
4.3.4. [Bis(1,10-phenanthroline)(tert-butyl 4-oxo-4-(1,10-
phenanthrolin-5-ylamino)butylcarbamate)]ruthenium
(II) bis(hexafluorophosphate), [Ru(phen)2(BOC-5-ngap)]
(PF6)2, 2d. Filtration of the product afforded 195 mg (46%)
of an orange-red solid; dH (500 MHz, CD3CN): 1.91 (q, 2H,
JZ7.1 Hz, CH2), 2.63 (t, 2H, JZ7.1 Hz, CH2), 3.21 (c, 2H,
JZ6.4 Hz, CH2), 5.53 (br s, 1H, NH), 7.59 (dd, 1Hb, JZ8.1,
5.1 Hz), 7.62–7.67 (m, 5Hb), 7.95 (dd, 1Ha, JZ5.1, 0.7 Hz),
8.01–8.07 (m, 5Ha), 8.27 (s, 4H), 8.54 (d, 1Hg, JZ8.0 Hz),
8.60–8.62 (m, 4Hg), 8.70 (s, 1H), 8.82 (d, 1Hg, JZ8.0 Hz),
9.25 (broad s, 1H, NH); dC (125 MHz, CD3CN): 26.53
(CH2), 28.07 (CH3), 34.23, 39.74 (CH2), 78.92 (CMe3),
117.72 (C), 125.61 (CH), 126.27 (C), 126.29 (CH), 126.37,
127.16 (C), 128.44 (CH), 131.23, 131.40 (C), 132.68 (CH),
134.48 (C), 136.58, 137.18 (CH), 146.05, 148.31, 148.34,
148.71 (C), 152.25, 153.32, 153.36, 153.40, 153.45 (CH),
4.3.1. [Bis(1,10-phenanthroline)(2-iodo-N-1,10-phenan-
throlin-5-ylacetamide)]ruthenium(II) bis(hexafluoro-
phosphate), [Ru(phen)2(5-iap)](PF6)2, 2a. Filtration of
the product affords 230 mg (55%) of an orange solid; dH
(500 MHz, CD3CN): 4.12 (s, 0.6H, CH2), 4.47 (s, 1.4H,
CH2), 7.60–7.71 (m, 6Hb), 7.98–8.11 (m, 6Ha), 8.28 (s, 4H),
8.61–8.64 (m, 4Hg), 8.65–8.76 (m, 2Hg), 9.40 (s, 0.3H,
NH), 9.45 (s, 0.7H, NH); dC (125 MHz, CD3CN): 0.01, 0.57
(CH2), 121.13, 121.89, 126.43, 126.88, 127.03, 127.07
(CH), 127.94 (C), 129.03 (CH), 131.53, 131.58, 131.99,
132.00 (C), 132.97, 133.25 (CH), 134.10, 134.40 (C),
137.32, 137.37, 137.78 (CH), 147.00, 148.87, 148.90,
148.92, 148.93, 149.37 (C), 153.23, 153.40, 153.92,
153.95, 154.03, 154.06, 154.08 (CH), 166.85 (CO), 168.69
(CO); m/z (ESI) Z412.5 [M]2C. Anal. Calcd for [C38H26
IN7ORu](PF6)2: C, 40.95; H, 2.35; N, 8.80%, found: C,
40.63; H, 2.41; N, 8.64%.
157.08 (NHCO2), 173.14 (NHCO); m/z (ESI) Z421 [M]2C
.
Anal. Calcd for [C45H40N8O3Ru](PF6)2: C 47.75, H 3.56, N
9.90%, found: C, 47.68; H, 3.90; N, 9.87%.
Acknowledgements
4.3.2. [Bis(1,10-phenanthroline)(4-oxo-4-(1,10-phenan-
throlin-5-ylamino)butanoic acid)]ruthenium(II) bis(hexa-
fluorophosphate), [Ru(phen)2(5-suap)](PF6)2, 2b. Filtration
of the product afforded 141 mg (36%) of an orange solid; dH
(500 MHz, CD3CN): 2.77 (t, 2H, JZ6.2 Hz, CH2), 2.92 (t,
2H, JZ6.2 Hz, CH2), 7.59 (dd, 1Hb, JZ8.3, 5.0 Hz), 7.62–
We gratefully acknowledge the European Union for
financial support of this research (grants ICA4-2001-
10022, ‘Solwater’, and ICA3-CT-2002-10016, ‘Aquacat’),
and the Spanish Ministry of Education and Science (ref.
BQU2002-04515-C02).

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