Synthesis, structure and photo-physical properties of phosphorus-supported fluorescent probes

Article abstract of DOI:10.1016/j.tet.2011.06.073

Various phosphorus-supported fluorescent probes have been synthesized by the condensation reaction of multi-functional phosphorus hydrazides with various fluorophore-containing carboxaldehydes. Compounds, thus prepared, in this study are (PhO)₂

Full text of DOI:10.1016/j.tet.2011.06.073

Tetrahedron 67 (2011) 6917e6926
Contents lists available at ScienceDirect
Tetrahedron
journal homepage: www.elsevier.com/locate/tet
Synthesis, structure and photo-physical properties of phosphorus-supported
fluorescent probes
*
Vadapalli Chandrasekhar , Mrituanjay D. Pandey, Biswanath Das, Bani Mahanti,
Kandasamy Gopal, Ramachandran Azhakar
Department of Chemistry, Indian Institute of TechnologydKanpur, Kanpur 208016, India
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 27 May 2011
Received in revised form 16 June 2011
Accepted 23 June 2011
Available online 28 June 2011
Various phosphorus-supported fluorescent probes have been synthesized by the condensation reaction
of multi-functional phosphorus hydrazides with various fluorophore-containing carboxaldehydes.
Compounds, thus prepared, in this study are (PhO)2P(O)[N(Me)eN]CHeR] (1a, 1b), Ph2P(O)[N(Me)eN]
CHeR] (2b, 2c, 2d), PhP(O)[N(Me)eN]CHeR]2 (3b, 3c), P(S)[N(Me)eN]CHeR]3 (4b, 4c), P(O)[N(Me)e
N]CHeR]3 (5a, 5b, 5c), N3P3(O2C12H8)2[N(Me)eN]CHeR]2 (6a, 6b, 6c), N3P3(O2C12H8)[N(Me)eN]
CHeR]4 (7a, 7b, 7c, 7d) and N3P3[N(Me)eN]CHeR]6 (8b, 8c), where R¼1-pyrenyl (a), 9-anthracenyl (b),
9-phenanthryl (c) and 7-(N,N0-diethylamino)-3-coumarinyl (d). All of these compounds have been char-
acterized by various analytical techniques including 31P{1H} NMR spectroscopy. Compounds 1b, 2b, 3b,
4b, 5b, 5c and 6d have also been characterized by single crystal X-ray analysis. All of these phosphorus-
supported compounds exhibit excellent fluorescence properties in aqueous solution at near physiological
conditions.
Keywords:
Phosphorus-supported ligands
Hydrazides
Hydrazones
Fluorescence
Ó 2011 Elsevier Ltd. All rights reserved.
1. Introduction
prepare heteronuclear trimetallic 3de4f complexes.8 Some mem-
bers of the former family show NLO properties while some mem-
In recent years there have been efforts to utilize functional in-
organic rings and cages as scaffolds for assembling molecules that
possess dendrimer-like architectures. Thus, compounds, such as
cyclophosphazenes,1 cyclosiloxanes,2 borazines3 and AleN/C rings4
have been examined for this purpose. In all these cases the central
‘inorganic core’, which contains several reactive sites, are utilized
for introducing the required functional groups on the periphery of
the molecule. In this regard, we have been interested for some
time in the use of phosphorus hydrazides for the construction
of multi-site coordination ligands and for preparing electroactive
dendrimer-like compounds. Thus, we have shown that the reaction
of N3P3[N(Me)eNH2]6 with ferrocene carboxaldehyde affords
the hexaferrocene starburst-type compound N3P3[N(Me)eN]
CHeFc]6.5 Such hydrazides and related compounds have earlier
also been used, in pioneering studies, by Majoral and co-workers
for the construction of macrocycles, cryptands and dendrimers.6
The simple coordination properties of these compounds were ex-
amined by Katti and co-workers.7 We have been interested in
elaborating the chemistry of cyclic and acyclic phosphorus(V) hy-
drazides for a variety of reasons including assembling multi-
functional ligands. Such ligands have been used to build mono-
or trimetallic complexes while some others have been used to
bers of the latter family possess interesting magnetic properties
including single-molecule magnetism (SMM) behaviour. Though
a large number of phosphorus(V) hydrazone based ligands have
been studied over the years, their utility to assemble multi-
chromophoric constructs have remained unexplored. Accordingly,
in this paper, we describe the modular design, assembly and
structural characterization of a family of phosphorus-supported
hydrazones containing a variety of chromophores: (PhO)2P(O)
[N(Me)eN]CHeR] (1a, 1b), Ph2P(O)[N(Me)eN]CHeR] (2b, 2c,
2d), PhP(O)[N(Me)eN]CHeR]2 (3b, 3c), P(S)[N(Me)eN]CHeR]3
(4b,
4c),
P(O)[N(Me)eN]CHeR]3
(5a,
5b,
5c),
N3P3(O2C12H8)2[N(Me)eN]CHeR]2 (6a, 6b, 6c), N3P3(O2C12H8)
[N(Me)eN]CHeR]4 (7a, 7b, 7c, 7d) and N3P3[N(Me)eN]CHeR]6
(8b, 8c) where R¼1-pyrenyl (a), 9-anthracenyl (b), 9-
phenanthrenyl (c) and 7-(N,N0-diethylamino)-3-coumarinyl (d).
The variation of the fluorescent group on the periphery of the
phosphorus-supported construct from one to six in a well-planned
modular manner results in interesting fluorescence behaviour.
2. Results and discussion
2.1. Synthesis and structure
A series of fluorophore-containing acyclic phosphorous hydra-
zones, 1aeb, 2aed (monohydrazones); 3aed (dihydrazones) and
* Corresponding author. Tel.: þ91 512 259 7259; fax: þ91 512 259 7436; e-mail
address: vc@iitk.ac.in (V. Chandrasekhar).
0040-4020/$ e see front matter Ó 2011 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tet.2011.06.073

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V. Chandrasekhar et al. / Tetrahedron 67 (2011) 6917e6926
4aed, 5aec (trihydrazones) have been synthesized by a two-step
synthetic protocol. The first step involved the regiospecific re-
action of N-methylhydrazine with an appropriate phosphorus ha-
lide [Ph2P(O)Cl, (PhO)2P(O)Cl, PhP(O)Cl2 and P(O)Cl3] affording the
corresponding hydrazides: Ph2P(O)[N(Me)NH2], (PhO)2P(O)[N(Me)
NH2], PhP(O)[N(Me)NH2]2 and P(O)[N(Me)NH2]3 (Scheme 1). Each
of these functional hydrazides are endowed with reactive eNH2
groups. Utilizing the reactivity of the latter condensation of the
hydrazides with a fluorophore-containing carboxaldehyde [pyr-
ene-1-carboxaldehyde (a), anthracene-9-carboxaldehyde (b),
phenanthrene-9-carboxaldehyde (c) and 7-(N,N0-diethylamino)-
coumarin-3-aldehyde (d)] afforded phosphorus-supported hydra-
zones, which contained the fluorophores as pendant groups, in
near quantitative yields (Scheme 1). Utilizing a similar procedure,
except replacing the acyclic phosphorus halides with chlor-
ocyclophosphazenes (N3P3Cl2(O2C12H8)2, N3P3Cl4(O2C12H8) and
N3P3Cl6) resulted in the assembly of the formation of the multi-
chromophoric cyclotriphosphazene constructs: 6aed (dihy-
drazones), 7aed (tetrahydrazones) and 8aed (hexahydrazones)
(Scheme 2). All of these phosphorus-supported hydrazides and
hydrazones are very lipophilic and are soluble in a wide range of
organic solvents. The synthetic details and characterization data of
some of these compounds viz., 2a, 3a, 3d, 4a, 4d, 6d, 8a and 8d have
been described by us earlier.9 All the other compounds have been
well characterized by 31P{1H} NMR spectroscopy (Table 1). In ad-
dition, these compounds have also been characterized by various
spectroscopic methods viz. IR, 1H NMR and ESIeHRMS (see
Experimental section). Compounds 1b, 2b, 3b, 4b, 5b, 5c and 6d
have also been characterized by single crystal X-ray analysis.
The molecular structures of compounds 1b, 2b, 3b, 4b, 5b, 5c
and 6d are shown in Fig. 1aeg and their selected bond parameters
are given in Table 2.
Compound 1b crystallizes in the orthorhombic crystal system
(space group: P212121), 2b in the monoclinic crystal system (space
group: P21/n) while 3b, 4b, 5b and 6d crystallize in the triclinic
crystal system (space group: Pꢀ1). Compound 5c crystallizes in the
monoclinic crystal system (space group: C2/c). The molecular
structure of the acyclic phosphorous hydrazones compounds are
fairly similar and show a distorted tetrahedral phosphorus atom
that acts as a pivot to anchor the chromophoric pendant groups
ꢀ
(Fig. 1). The P]O bond distances observed in 1b (1.452 (2) A), 2b
ꢀ
ꢀ
ꢀ
ꢀ
(1.477 (2) A), 3b (1.474 (2) A), 5b (1.443 (3) A) and 5c (1.455 (5) A)
are very close to each other and are comparable with the literature
values (Table 2).10 Similarly, the P]S bond distance in 4b is 1.925
10
ꢀ
(2) A, which is also comparable with the literature values. The
PeN bond distances in 1be5b and 5c are 1.651 (3), 1.677 (2), 1.686
ꢀ
(2), 1.674 (2), 1.654 (4) and 1.678 (6) A, respectively, which are
ꢀ
comparable with the PeN single bond distance of w1.70 A found in
the literature (Table 2).11
The molecular structure of 6d shows two 2,20-biphenoxy units
that are attached to P1 and P2 in a spirocyclic manner and are
perpendicular to the plane of the cyclophosphazene core (Fig. 1g).
The other phosphorous atom, P3 contains the two hydrazone units
ꢀ
(N4 and N7). The average PeN bond distance of 1.58 A observed for
the cyclophosphahzene ring (P3N3 ring) is smaller than the exo-
ꢀ
cyclic average PeN bond distances of 1.68 A. In general, the PeN
bond distances within the P3N3 ring are non-equivalent for com-
pounds of the type gem-N3P3X2Y4.12 Accordingly in the present
Scheme 1. Synthesis of compounds 1e5. R¼1-pyrenyl (a); 9-anthracenyl (b); 9-phenanthryl (c) and 7-(N,N0-diethylamino)-3-coumarinyl (d).

V. Chandrasekhar et al. / Tetrahedron 67 (2011) 6917e6926
6919
Scheme 2. Synthesis of compounds 6e8. R¼1-pyrenyl (a); 9-anthracenyl (b); 9-phenanthryl (c) and 7-(N,N0-diethylamino)-3-coumarinyl (d).
Table 1
Summary of the 31P{1H} NMR spectra of various precursors and hydrazone products
S.No
P-Halide
P-Hydrazide
P-Hydrazone
1
(PhO)2P(O)Cl ꢀ4.7 (s)
(PhO)2P(O)[N(Me)eNH2] 0.30
(s, 1P, PO)
Ph2P(O)[N(Me)eNH2] 32.75
(s, 1P, PO)
(PhO)2P(O)[N(Me)eN]CHeR] (1a): ꢀ5.01 (s)
(PhO)2P(O)[N(Me)eN]CHeR] (1b): ꢀ5.06 (s)
Ph2P(O)[N(Me)eN]CHeR] (2b); 32.76 (s)
Ph2P(O)[N(Me)eN]CHeR] (2c): 30.82 (s)
Ph2P(O)[N(Me)eN]CHeR] (2d): 32.38 (s)
PhP(O)[N(Me)eN]CHeR]2 (3b): 25.54 (s)
PhP(O)[N(Me)eN]CHeR]2 (3c): 27.19 (s)
P(S)[N(Me)eN]CHeR]3 (4b): 74.64 (s)
P(S)[N(Me)eN]CHeR]3 (4c): 75.20 (s)
P(O)[N(Me)eN]CHeR]3 (5a): 16.36 (s)
P(O)[N(Me)eN]CHeR]3 (5b): 16.45 (s)
P(O)[N(Me)eN]CHeR]3 (5c): 16.85 (s)
N3P3(O2C12H8)2[N(Me)eN]CHeR]2 (6a):
19.8 (t, 1P, P(N(Me)eN]CHeR), 26.6 (d,
2P, P(O2C12H8)) 3J(PeNeP)¼70.9 Hz.
N3P3(O2C12H8)2[N(Me)eN]CHeR]2 (6b):
19.0 (t, 1P, P(N(Me)eN]CHeR), 26.4
(d, 2P, P(O2C12H8)) 3J(PeNeP)¼70.9 Hz.
N3P3(O2C12H8)2[N(Me)eN]CHeR]2 (6c):
19.8 (t, 1P, P(N(Me)eN]CHeR), 26.6
(d, 2P, P(O2C12H8)) 3J(PeNeP)¼70.9 Hz.
N3P3(O2C12H8)[N(Me)eN]CHeR]4 (7a):
19.9 (d, 2P, P(N(Me)eN]CHeR), 26.8
(t, 1P, P(O2C12H8)) 3J(PeNeP)¼65.4 Hz.
N3P3(O2C12H8)[N(Me)eN]CHeR]4 (7b):
18.5 (d, 2P, P(N(Me)eN]CHeR), 26.0
(t, 1P, P(O2C12H8)) 3J(PeNeP)¼70.9 Hz.
N3P3(O2C12H8)[N(Me)eN]CHeR]4 (7c):
19.7 (d, 2P, P(N(Me)eN]CHeR), 26.6
(t, 1P, P(O2C12H8)) 3J(PeNeP)¼70.9 Hz.
N3P3(O2C12H8)[N(Me)eN]CHeR]4 (7d):
20.2 (d, 2P, P(N(Me)eN]CHeR), 26.7
(t, 1P, P(O2C12H8)) 3J(PeNeP)¼65.4 Hz.
P3N3[N(Me)eN]CHeR]6 (8b): 17.31 (s)
P3N3[N(Me)eN]CHeR]6 (8c): 18.92 (s)
2
Ph2P(O)Cl 44.9 (s)
3
4
5
PhP(O)Cl2 39.7 (s)
P(S)Cl3 31.7 (s)
P(O)Cl3 ꢀ2.1 (s)
PhP(O)[N(Me)eNH2]2 29.9
(s, 1P, PO)
P(S)[N(Me)eNH2]3 84.5
(s, 1P, PS)
P(O)[N(Me)eNH2]3 26.0
(s, 1P, PO)
6
N3P3Cl6 19.5 (s)
N3P3(O2C12H8)2 [N(Me)eNH2]2
26.6 (d, 2P, P(O2C12H8)2), 29.3
(t, 1P, P(N(Me)eNH2),
N3P3Cl2(O2C12H8)2 19.8
3J(PeNeP)¼58.2 Hz.
(d, 2P, P(O2C12H8)), 29.2
(t, 1P, PCl2) 3J(PeNeP)¼80 Hz.
7
N3P3Cl6 19.5 (s)
N3P3(O2C12H8) [N(Me)eNH2]4
27.2 (t, 1P, P(O2C12H8)), 29.9
(d, 2P, P(N(Me)eNH2),
3J(PeNeP)¼53.4 Hz.
N3P3Cl4(O2C12H8) 13.3
(dd, 1P, P(O2C12H8)), 25.2
(d, 2P, PCl2), 3J(PeNeP)¼71 Hz.
8
N3P3Cl6 19.5 (s)
N3P3[N(Me)eNH2]6 29.5
(s, 3P, N3P3 ring)

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V. Chandrasekhar et al. / Tetrahedron 67 (2011) 6917e6926
Fig. 1. Molecular structures of 1b (a), 2b (b), 3b (c), 4b (d), 5b (e), 5c (f) and 6d (g) are shown with 50% ellipsoidal probability level (ORTEP diagrams).

V. Chandrasekhar et al. / Tetrahedron 67 (2011) 6917e6926
6921
Table 2
Selected bond parameters for the crystal structures of 1b, 2b, 3b, 4b, 5b, 5c and 6d
Bond angle (ꢁ)
ꢀ
Structure
Bond length (A)
1b
P1eO2 1.452 (2)
P1eO3 1.584 (2)
P1eO1 1.578 (2)
P1eN1 1.651 (2)
O2eP1eO1 115.86 (12)
O1eP1eO3 100.15 (11)
O1eP1eN1 103.79 (11)
O1eP1eN1 117.77 (11)
N1eP1eC16 104.37 (11)
N1eP1eC22 103.30 (11)
O1eP1eN3 110.28 (10)
N3eP1eN1 104.63 (10)
N3eP1eC1 109.54 (11)
N1eP1eN3 104.83 (13)
N3eP1eN5 106.37 (13)
N3eP1eS1 113.42 (10)
O1eP1eN3 112.1 (2)
N3eP1eN1 108.29 (19)
N3eP1eN5 106.35 (19)
O1eP1eN3 113.3 (3)
N3eP1eN1 107.3 (3)
N3eP1eN5 105.4 (2)
N1eP1eN2 117.5 (2)
N1eP1eO2 113.2 (2)
N2eP1eO2 105.3 (2)
N3eP2eO3 113.1 (2)
N3eP2eO4 105.2 (2)
O3eP2eO4 102.20 (18)
N1eP3eN7 110.0 (2)
N1eP3eN4 111.0 (2)
N7eP3eN4 106.0 (2)
O2eP1eO3 115.99 (11)
O2eP1eN1 113.04 (13)
O3eP1eN1 106.48 (11)
O1eP1eC16 113.06 (11)
O1eP1eC22 111.63 (11)
C16eP1eC22 105.53 (11)
O1eP1eN1 113.08 (11)
O1eP1eC1 113.49 (11)
N1eP1eC1 105.34 (11)
N1eP1eN5 103.99 (13)
N1eP1eS1 115.05 (10)
N5eP1eS1 112.29 (10)
O1eP1eN1 110.35 (19)
O1eP1eN5 114.7 (2)
2b
3b
4b
5b
5c
6d
C16eP1 1.798 (3)
N1eP1 1.676 (2)
C22eP1 1.805 (3)
O1eP1 1.477 (2)
C1eP1 1.788 (3)
N3eP1 1.670 (2)
N1eP1 1.685 (2)
O1eP1 1.474 (2)
N1eP1 1.673 (2)
N5eP1 1.677 (3)
N3eP1 1.673 (3)
P1eS1 1.926 (1)
P1eO1 1.443 (3)
P1eN1 1.655 (4)
P1eN3 1.653 (4)
P1eN5 1.659 (4)
P1eO1 1.455 (5)
P1eN1 1.678 (6)
P1eN3 1.667 (5)
P1eN5 1.684 (5)
O1eP1eN1 112.5 (3)
O1eP1eN5 111.8 (2)
N1eP1 1.576 (4)
N2eP2 1.574 (4)
N3eP2 1.567 (4)
N4eP3 1.681 (4)
O1eP1 1.583 (3)
O3eP2 1.588 (4)
N1eP3 1.590 (4)
N2eP1 1.587 (4)
N3eP3 1.601 (4)
N7eP3 1.662 (4)
O2eP1 1.593 (3)
O4eP2 1.597 (3)
O1eP1eN2 111.0 (2)
O1eP1eO2 102.6 (2)
N3eP2eN2 118.7 (2)
N2eP2eO3 103.3 (2)
N2eP2eO4 113.4 (2)
N1eP3eN3 116.5 (2)
N3eP3eN7 108.2 (2)
N3eP3eN4 104.5 (2)
instance also four different types of bond distances are observed
changing the number of chromophoric groups, absorption maxima
): 265 (1.96ꢂ104), 375 (2.3ꢂ103)
ꢀ
(Table 2). A long distance of 1.601 (4) A (P3eN3) and a short dis-
also changes arbitrarily [cf. lmax
(
3
tance of 1.576 (4) A (P1eN1) are observed. In addition, two other
for 1a; 266 (7.2ꢂ104), 371 (1.1ꢂ104) for 5a; 262 (4.9ꢂ104), 375
(1.0ꢂ104) for 6a; 295 (1.24ꢂ104), 371 (1.4ꢂ104) for 7a] (Fig. 3). The
observed spectra are typical for fluorophore-containing com-
ꢀ
types of PeN distances are also observed within the P3N3 ring as
ꢀ
follows, 1.574 (4) and 1.590 (4) A for P2eN2 and P3eN1; 1.587 (4)
13
and 1.567 (4) A for P1eN2 and P2eN3, respectively. Within the
P3N3 ring the bond angle at P3 is the smallest (116.5 (2)ꢁ), while
those observed at P2 (118.6 (2)ꢁ) and P1 (117.5 (2)ꢁ) are wider than
the ideal values. Also the bond angles at nitrogen atoms are much
wider than the ideal values. These trends are in keeping with sp3
hybridization at phosphorus and an approximate sp2 hybridization
at nitrogen. The cyclophosphazene ring in 6d is non planar; P1, P3,
N1 are in one plane while N2, P2, N3 are in the other plane and
showing the dihedral angle of 37.8ꢁ between them (Fig. 2). Two
pounds and the absorptions are due to aromatic pe
p* transi-
ꢀ
tions.8,9,14 The fluorescence spectra of all the four type of probes
viz. pyrene (lext¼363 nm), anthracene (lext¼255 nm), phenan-
threne (lext¼255 nm) and coumarin (lext¼413 nm) showed broad
as well sharp peaks in the HEPES buffer (9:1 v/v of H2O/DMSO,
10 mM, pH¼7.4) solution (Fig. 4; Table 3). The pyrene series
showed a broad band at 465 nm (5a and 7a), 470 nm (6a) and
505 nm (1a). Interestingly, 5a and 7a showed higher intensity
when compared to other compounds but 1a showed emission
band at longer wavelength. The anthracene series showed a broad
ꢀ
types of exocyclic PeN distances found at P3 are P3eN4 1.681 (4) A
and P3eN7 1.662 (4) A.
ꢀ
The crystal packing of all these compounds showed strong intra-
and intermolecular hydrogen bonding interactions (CH/O,
Table 3
CeH/
p
and
p/p
) that leads to the formation of various supra-
Spectroscopic data of 1e8
moleculer architectures. These aspects are not discussed here.
Compounds
lmax/nm (
3
ꢂ10ꢀ4
)
lem/nm
vF
1a
1b
2b
2c
2d
3b
3c
4b
4c
5a
5b
5c
6a
6b
6c
7a
7b
7c
7d
8b
8c
265 (2.0), 377 (0.27)
257 (2.6), 272 (2.4), 394 (0.28)
245 (1.4), 278 (1.6), 396 (0.28)
257 (2.1), 320 (1.5)
294 (0.47), 444 (1.8)
260 (2.2), 402 (0.6)
258 (1.7), 319 (0.11)
263 (0.8), 378 (0.16)
256 (3.5), 327 (0.19)
266 (7.0), 372 (1.05)
247 (1.1), 283 (1.2), 361 (0.5)
258 (1.1), 339 (0.71)
261 (4.9), 367 (7.1)
256 (3.8), 389 (0.15)
251 (1.0), 329 (0.38)
290 (1.2), 372 (1.35), 396 (1.1)
266 (2.5), 366 (0.5)
505
0.009
0.001
0.003
0.002
0.049
0.002
0.003
0.001
0.002
0.010
0.001
0.001
0.011
0.002
0.001
0.016
0.001
0.002
0.022
0.001
0.003
388, 408, 422
394, 448
338
516
360, 396, 421
374
428, 451
376
467
393, 424
375, 421
471
Fig. 2. Cyclophosphazene ring plane of compounds 6d.
362, 392, 419
369, 414
468
357, 426
370
530
361, 390, 413
370
2.2. Absorption and emission spectra
The spectroscopic data of all the ligands are given in the Table 3.
The absorption spectra of all the compounds in HEPES buffer (9:1
v/v of H2O/DMSO, 10 mM, pH¼7.4) are characterized by peaks both
at high and low energies. In general, it has been found that on
255 (2.5), 327 (1.2)
274 (4.6), 423 (7.7)
255 (4.0), 402 (0.8)
253 (3.2), 325 (1.1)

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V. Chandrasekhar et al. / Tetrahedron 67 (2011) 6917e6926
0.8
0.6
0.4
0.2
0.4
0.3
0.2
0.1
0.0
(b)
(a)
1b
2b
3b
4b
5b
6b
7b
8b
1a
5a
6a
7a
0.0
0.3
(c)
(d)
0.6
0.3
0.0
2c
3c
4c
5c
6c
7c
8c
2d
7d
0.2
0.1
0.0
300
700
400
500
600
700
300
400
500
600
Wavelength (nm)
Fig. 3. UVevis spectra of pyrene series (a), anthracene series (b), phenanthrene series (c) and coumarin series (d). Concentration of the HEPES buffer solution: 10.0
of H2O/DMSO; pH¼7.4.
mM; 9:1 mixture
500
(a)
(b)
225
150
75
1b
2b
3b
4b
5b
6b
7b
8b
400
300
200
100
0
1a
5a
6a
7a
0
400
500
600
700
350
400
450
500
400
180
150
120
90
(c)
(d)
2c
3c
4c
5c
6c
7c
8c
300
200
100
0
2d
7d
60
30
0
350
400
450
450
500
550
600
650
700
Wavelength (nm)
Fig. 4. (a) Fluorescence spectra of pyrene series (lext¼363 nm); (b) Fluorescence spectra of anthracene series (lext¼255 nm); (c) Fluorescence spectra of phenanthrene series
lext¼255 nm) and (d) Fluorescence spectra of coumarin series (lext¼413 nm). Concentration of the HEPES buffer solution: 10.0 M; 9:1 mixture of H2O/DMSO; pH¼7.4.
(
m
band at w420 nm along with some higher energy shoulders; 6b
showed a slightly higher intensity and more red-shifted emission
bands. The phenanthrene series showed a broad band emission at
w370 nm with higher intensity for 3c and 8c, while 5c showed
a comparatively lower intensity. The coumarin series showed
a broad band emission at w515 nm with 2d showing a higher
intensity than 7d.
3. Conclusion
We have shown a new synthetic strategy to build multi-
chromophore containing molecular assemblies. Our methodology
consists of utilizing phosphorus hydrazides as the functional pre-
cursors that could be elaborated by a condensation reaction strat-
egy to the corresponding hydrazones. The type of aldehyde used

V. Chandrasekhar et al. / Tetrahedron 67 (2011) 6917e6926
6923
governs the property of the assembly. The number and orientation
of such aldehydes allow a modulation of the property. Accordingly,
in this study, we have shown the possibility to obtain photoactive
assemblies using phosphorus atoms as the structural supports.
Studies exploring the utility of such compounds in various appli-
cations including selective sensing of metal ions is underway.
QUATTRO II triple quadruple mass spectrometer. The ESI capillary
was set at 3.5 kV and the cone voltage was 40 V. Steady state ab-
sorption and emission spectra were recorded on
a Per-
kineElmereLambda 20 spectrophotometer and Varian Cary
Eclipsed fluorimeter using a 10 mm quartz cell at room tempera-
ture. All the fluorescence measurements were taken on variable slit
width ranging from 5:5 for pyrene series compounds, 10:10 for
anthracene and phenanthrene series compounds and 5:2.5 for
coumarin series compounds. In each case, the fluorescence quan-
tum yield was determined by comparing the emission intensity of
4. Experimental section
4.1. Reagents
the sample with that of anthracene (
cenyl and phenanthryl derivatives) and fluorescein (
0.1 N NaOH (for coumarinyl derivatives) using the equation:17
fU
fR(FuAR/FRAU)(nU/nR)2, where fU and fR are the fluorescence
quantum yield of the sample and reference; FU and FR are the area
under the fluorescence spectra of the sample and reference; AU and
AR are the absorbance of the sample and reference (at the excitation
wavelength); nU and nR are the refractive indices of the solvent
used for the sample and reference.
f
¼0.27) (for pyrenyl, anthra-
f
¼0.85) in
Solvents were received from S. D. Fine chemicals (India) and
purified prior to use. (PhO)2P(O)Cl, Ph2P(O)Cl, PhP(O)Cl2, pyrene-1-
carboxaldehyde, anthracene-9-carboxaldehyde, phenanthrene-9-
carboxaldehyde, 4-diethylaminosalicylaldehyde, diethylmalonate,
2,20-dihydroxybiphenyl, hexachlorocyclotriphosphazene (N3P3Cl6)
and pipyridine were purchased from SigmaeAldrich, USA. (S)PCl3
and (O)PCl3 were purchased from Fluka (Switzerland). All the
phosphorus hydrazones15 and 7-(N,N0-diethylamino)-coumarin-3-
aldehyde16 were synthesized using reported procedures. N-Meth-
ylhydrazine (MeeNHeNH2) was obtained as a gift from the Vikram
Sarabhai Space Research Centre, Thiruvananthapuram, India and
has been used as such.
¼
4.3. Crystallography
Crystals suitable for X-ray diffraction were grown in a 1:1
mixture of CHCl3/MeOH solution, except 6d, which was grown from
a 1:1 mixture of CH2Cl2/CHCl3 solution. The single crystal X-ray
4.2. Measurements
data for 1b, 2b, 3b, 4b, 5b, 5c and 6d were collected on a Bruker
ꢀ
Melting points were measured using a JSGW melting point ap-
paratus and are uncorrected. IR spectra were recorded as KBr pel-
lets on a Bruker Vector-22 FTIR spectrophotometer operating from
400 to 4000 cmꢀ1. 1H, 13C and 31P{1H} NMR spectra were obtained
on a JEOL-JNM LAMBDA 400 or JEOL-DELTA2 500 model spec-
trometer operating at 400 or 500 MHz (for 1H), 100 or 125 MHz (for
13C) and 202.5 MHz (for 31P) in CDCl3 solutions at room tempera-
ture. The chemical shifts are referenced with respect to TMS (for 1H
and 13C) or 85% H3PO4 (for 31P). Electrospray ionizationehigh res-
olution mass spectra (ESIeHRMS) were recorded on a MICROMASS
SMART APEX CCD diffractometer (Mo K
Complete hemispheres of data were collected using
a
,
l
¼0.71073 A, 100 K).
u
-scans (0.3ꢁ,
up to 30 s/frame). Integrated intensities were obtained with
SAINTþ.18a Absorption corrections, where necessary, were made
using SADABS.18b Structure solution and refinement was performed
with the SHELXTL-package.18c The structures were solved by direct
methods and completed by iterative cycles of DF syntheses and full-
matrix least-squares refinement against F2.18c Non-hydrogen atoms
were refined with anisotropic displacement parameters. Details of
the data collection and refinement parameters are given in Table 4.
Table 4
Crystallographic data and structure refinement details for 1be6b
1b
2b
3b
4b
5b
5c
6d
Empirical formula
Formula weight
Temperature (K)
Crystal system
Space group
C28H23N2O3P
466.45
100 (2)
Orthorhombic
P212121
5.951 (2)
16.063 (6)
23.803 (8)
90
C28H23N2OP
434.45
100 (2)
Monoclinic
P21/n
8.409 (3)
14.562 (6)
17.447 (7)
90
94.918 (7)
90
2128.4 (14)
4
C38H3N4OP
590.64
100 (2)K
Triclinic
Pꢀ1
C48H39N6PS
762.88
153 (2)
Triclinic
Pꢀ1
C49H40Cl3 N6OP
866.19
273 (2)
Triclinic
Pꢀ1
C48H39N6OP
746.82
100 (2)
Monoclinic
C2/c
32.718 (5)
15.104 (5)
18.160 (5)
90.00
96.33
90.00
8919 (4)
8
1.112
C111H108Cl8N18O16P6
2419.57
100 (2)
Triclinic
Pꢀ1
ꢀ
a (A)
10.847 (4)
11.951 (5)
13.148 (5)
77.937 (7).
67.022 (6)
69.184 (6)
1461.8 (9)
2
10.845 (5)
16.632 (5)
21.434 (5)
96.565 (5)
90.574 (5)
91.907 (5)
3838 (2)
4
11.122 (6)
13.445 (7)
14.471 (8)
81.166 (10)
82.114 (11)
82.625 (12)
2105.3 (19)
2
11.010 (4)
12.759 (4)
20.531 (7)
86.616
ꢀ
b (A)
ꢀ
c (A)
a
b
g
(ꢁ)
(ꢁ)
(ꢁ)
90
90
76.804
82.921
2785.3 (17)
1
1.443
3
ꢀ
V (A )
2275.3 (13)
4
1.362
0.155
976
Z
Dcalcd (mg/m3)
Abs. coeff. (mmꢀ1
F(000)
1.356
0.154
912
1.342
0.134
620
1.320
0.170
1600
1.366
0.302
900
)
0.102
3136
0.363
1254
Cryst size (mm3)
0.08ꢂ0.05ꢂ0.04 0.08ꢂ0.04ꢂ0.03 0.09ꢂ0.08ꢂ0.05 0.11ꢂ0.08ꢂ0.05 0.10ꢂ0.06ꢂ0.04 0.08ꢂ0.06ꢂ0.04 0.19ꢂ0.08ꢂ0.06
q
range (ꢁ)
2.13 to 26.5
ꢀ7ꢃhꢃ7
2.34 to 28.38
ꢀ11ꢃhꢃ11
ꢀ11ꢃkꢃ19
ꢀ23ꢃlꢃ22
13709/5282
2.14 to 26.5
ꢀ13ꢃhꢃ10
ꢀ14ꢃkꢃ14
ꢀ16ꢃlꢃ15
8471/5883
2.12 to 26.5
ꢀ13ꢃhꢃ13
ꢀ15ꢃkꢃ20
ꢀ24ꢃlꢃ26
22397/15530
2.21 to 25.0
ꢀ13ꢃhꢃ9
1.91 to 25.50
ꢀ39ꢃhꢃ25
ꢀ18ꢃkꢃ18
ꢀ20ꢃlꢃ22
20781/7530
1.96 to 26.0
ꢀ13ꢃhꢃ13
ꢀ9ꢃkꢃ15
Index ranges
ꢀ20ꢃkꢃ18
ꢀ23ꢃlꢃ29
13207/4702
ꢀ15ꢃkꢃ15
ꢀ16ꢃlꢃ17
10796/7258
ꢀ25ꢃlꢃ24
Reflections collected/unique
15689/10714
[R(int)¼0.0741] [R(int)¼0.0525] [R(int)¼0.0292] [R(int) ¼0.0429] [R(int)¼0.0658] [R(int)¼0.0958] [R(int)¼0.0463]
Data/restraints/parameters
4702/0/308
1.094
5282/0/290
1.098
5883/0/399
1.065
15530/0/1015
0.996
7530/336/509
0.958
10714/2/727
1.053
Goodness-of-fit on F2
0.976
Final R indices [I>2
s
(I)]
R1¼0.0530
wR2¼0.1182
R1¼0.0682
wR2¼0.1321
R1¼0.0604
wR2¼0.1458
R1¼0.0976
wR2¼0.1926
R1¼0.0627
wR2¼0.1610
R1¼0.0830
wR2¼0.1932
R1¼0.0679
wR2¼0.1670
R1¼0.1045
wR2¼0.2080
R1¼0.0899
wR2¼0.2255
R1¼0.1702
wR2¼0.2925
R1¼0.1203
wR2¼0.2909
R1¼0.1958
wR2¼0.3435
R1¼0.0923
wR2¼0.2478
R1¼0.1317
wR2¼0.2973
R indices (all data)
ꢀꢀ3
Largest diff peak and hole (e A ) 0.367 and ꢀ0.584 0.551 and ꢀ0.655 0.530 and ꢀ0.539 0.643 and ꢀ0.551 0.404 and ꢀ0.538 0.427 and ꢀ0.324 2.055 and ꢀ0.634

6924
V. Chandrasekhar et al. / Tetrahedron 67 (2011) 6917e6926
4.4. General procedure for the synthesis of compounds 1ae8c
Anal. Calcd for
C27H28N3O3P from ESIeHRMS (m/z):
[2dþH]þ¼calculated
474.1907,
found
474.1942;
[2d
The phosphorus hydrazones 1ae8c were synthesized by the
following literature methods.8,9,15 Quantitative amount of phos-
phorus hydrazide in MeOH (15 mL) was added dropwise to the
solution of corresponding fluorophore-containing carboxaldehyde
in hot MeOH (30 mL). The reaction mixture was stirred at 50 ꢁC for
6 h. The yellow precipitate obtained was filtered, washed with hot
methanol (2ꢂ5 mL) and recrystallized from a 1:1 mixture of
CH2Cl2/n-hexane at 0 ꢁC. The specific details of each reaction are
given below.
þNa]þ¼calculated 496.1766, found 496.1739; [2dþCH3OHþCH3
CNþH]þ¼calculated
547.2474,
found
547.2834;
[2(2d)þ
Na]þ¼calculated 969.3436, found 969.3644.
Compound 3b: Anthracene-9-carboxaldehyde (0.412 g,
2.00 mmol); {Ph2P(O)[N(Me)NH2]2} (0.214 g, 1.00 mmol). Yield:
0.448 g (76%). Mp: 208e210 ꢁC. FT-IR ( /cmꢀ1): 3424 (b), 3046 (m),
n
2926 (m), 1674 (s), 1621 (s), 1583 (s), 1515 (s), 1463 (s), 1439 (s), 1331
(s), 1245 (s), 1209 (s), 1156 (s), 979 (s), 735 (s). 1H NMR (400 MHz,
d/
ppm): 3.42 (d, 3H, eNCH3), 3J(1He31P)¼7.6 Hz, 7.05e8.29 (m, 22H,
Compound 1a: Pyrene-1-carboxaldehyde (0.69 g, 3.00 mmol);
{(PhO)2P(O)[N(Me)NH2]} (0.834 g, 3.00 mmol). Yield: 1.06 g, (72%).
anthracenyl/phenyl H), 8.55 (s, 1H, eCH]N). 13C NMR (100 MHz,
d/
ppm): 135.82, 133.55, 132.17, 131.31, 129.79, 128.64, 128.32, 126.81,
Mp: 118e120 ꢁC. FT-IR (
n
/cmꢀ1): 3667 (b), 3448 (m), 3040 (m),
126.04, 125.13, 125.03, 31.24. 31P{1H} NMR (202.5 MHz,
d/ppm):
2924 (m), 1614 (s), 1591 (s), 1489 (s), 1384 (s), 1287 (s), 1217 (s), 1191
25.54 (s). Anal. Calcd for C38H31N4OP from ESIeHRMS (m/z):
[3bþH]þ¼calculated 591.2314, found 591.2313; [3bþCH3OHþCH3
CNþH]þ¼calculated 664.2836, found 664.3214.
(s), 1072 (s), 1026 (s), 987 (s), 950 (s). 1H NMR (400 MHz,
d/ppm):
3.50 (d, 3H, eNCH3, 3J(1He31P)¼8.04 Hz), 7.17e8.62 (m, 19H, pyr-
enyl/phenyl H) and 8.64 (s, 1H, CH]N). 13C NMR (100 MHz,
d/ppm):
Compound 3c: Phenanthrene-9-carboxaldehyde (0.412 g,
2.00 mmol); {Ph2P(O)[N(Me)NH2]2} (0.214 g, 1.00 mmol). Yield:
150.60, 138.11, 131.94, 131.37, 130.62, 128.65, 128.09, 127.42, 125.78,
125.41, 125.29, 124.74, 122.47, 120.74, 32.50. 31P{1H} NMR
0.436 g (74%). Mp: 135 ꢁC. FT-IR ( /cmꢀ1): 3446 (b), 2925 (m), 2855
n
(202.5 MHz,
d
/ppm): ꢀ5.00 (s). Anal. Calcd for C30H23N2O3P from
(s), 1744 (s), 1690 (s), 1623 (s), 1525 (s), 1494 (s), 1447 (s), 1246 (s),
ESIeHRMS (m/z): [1aþH]þ¼calculated 491.1525, found 491.1523;
1203 (s), 1153 (s), 1109 (s), 1074 (s), 956 (s). 1H NMR (500 MHz,
d/
[2(1a)þH]þ¼calculated 981.2971, found 981.2972.
ppm): 3.43 (d, 3H, eNCH3, 3J(1He31P)¼11.85 Hz), 7.24e8.70 (m,
Compound 1b: Anthracene-9-carboxaldehyde (0.618 g,
3.00 mmol); {(PhO)2P(O)[N(Me)NH2]} (0.834 g, 3.00 mmol). Yield:
22H, phenanthrenyl/phenyl H), 9.51 (s, 1H, eCH]N). 13C NMR
(125 MHz,
d/ppm): 137.31, 137.19, 133.22, 133.16, 130.66, 12930,
0.97 g (70%). Mp: 120 ꢁC. FT-IR ( /cmꢀ1): 3450 (b), 3041 (m), 1590
n
128.87, 128.23, 127.14, 126.64, 125.41, 122.84, 122.38, 30.57. 31P{1H}
(s), 1488 (s), 1286 (s), 1191 (s), 988 (s), 950 (s). 1H NMR (500 MHz,
d/
NMR (202.5 MHz, d/ppm): 27.19 (s). Anal. Calcd for C38H31N4OP
ppm): 3.49 (d, 3H, eNCH3, 3J(1He31P)¼8.0 Hz), 7.16e8.49 (m, 19H,
from ESIeHRMS (m/z): [3cþH]þ¼calculated 591.2314, found
591.2312; [3cþCH3OHþCH3CNþH]þ¼calculated 664.2836, found
664.3217; [2(3c)þH]þ¼calculated 1181.4549, found 1181.4579.
Compound 4b: Anthracene-9-carboxaldehyde (0.618 g,
3.00 mmol); {P(S)[N(Me)NH2]3} (0.214 g, 1.00 mmol). Yield: 0.594 g
anthracenyl/phenyl H), 8.6 (s, 1H, CH]N). 13C NMR (125 MHz,
d/
ppm): 150.60, 138.54, 131.49, 130.11, 128.98, 126.60, 125.37, 125.12,
120.71, 120.74, 32.62. 31P{1H} NMR (202.5 MHz,
d/ppm): ꢀ5.06 (s).
Anal. Calcd for C28H23N2O3P from ESIeHRMS (m/z):
[MþH]þ¼calculated
467.1525,
found
467.1521;
[2(1b)þ
(78%). Mp: 250e252 ꢁC. FT-IR (
(m), 1675 (s), 1662 (s), 1462 (s), 1257 (s), 1228 (s), 1147 (s), 954 (s),
n
/cmꢀ1): 3435 (b), 3047 (m), 2926
H]þ¼calculated 933.2971, found 933.3032.
Compound 2b: Anthracene-9-carboxaldehyde (0.618 g,
731 (s), 597 (s). 1H NMR (400 MHz,
d
/ppm)¼3.53 (d, 9H, eNCH3,
3.00 mmol); {Ph2P(O)[N(Me)NH2]} (0.738 g, 3.00 mmol). Yield:
3J(1He31P)¼12.44 Hz), 6.71e8.26 (m, 27H, anthracenyl H), 8.33 (s,
1.01 g, (78%). Mp: 150 ꢁC. FT-IR (
n
/cmꢀ1): 3422 (b), 3072 (m), 1590
2H, eCH]N). 13C NMR (100 MHz,
d/ppm): 135.89, 135.74, 131.16,
(s), 1662 (s), 1591 (s), 1246 (s), 1205 (s), 1157 (s), 1123 (s), 1102 (s),
129.66, 128.28, 127.76, 127.41, 125.67, 125.15, 124.83, 32.78. 31P{1H}
987 (s), 966 (s), 749 (s). 1H NMR (400 MHz,
d/ppm): 3.51 (d, 3H,
NMR (202.5 MHz, d/ppm): 74.64 (s). Anal. Calcd for C48H39N6SP
eNCH3, 3J(1He31P)¼12.0 Hz), 7.15e8.80 (m, 19H, anthracenyl/phe-
from ESIeHRMS (m/z): [4bþH]þ¼calculated 763.2773, found
763.2770; [4bþCH3OHþH]þ¼calculated 795.3035, found 795.2681.
Compound 4c: Phenanthrene-9-carboxaldehyde (0.618 g,
3.00 mmol); {P(S)[N(Me)NH2]3} (0.214 g, 1.00 mmol). Yield: 0.534 g
nyl H), 8.83 (s, 1H, CH]N). 13C NMR (125 MHz,
d/ppm): 162.74,
131.83, 131.02, 129.75, 128.40, 127.36, 127.03, 125.74, 123.14, 122.71,
34.62. 31P{1H} NMR (202.5 MHz,
d/ppm): 32.76 (s). Anal. Calcd for
C28H23N2O3P from ESIeHRMS (m/z): [2bþH]þ¼calculated
(70%). Mp: 120 ꢁC. FT-IR ( /cmꢀ1): 3440 (b), 2924 (m), 1568 (m),
n
435.1626, found 435.1620.
1493 (s), 1449 (s), 1246 (s), 1148 (s), 953 (s), 825 (s), 747 (s). 1H NMR
Compound 2c: Phenanthrene-9-carboxaldehyde (0.618 g,
3.00 mmol); {Ph2P(O)[N(Me)NH2]} (0.738 g, 3.00 mmol). Yield:
(500 MHz,
d
/ppm): 3.58 (d, 9H, eNCH3, 3J(1He31P)¼9.1 Hz),
7.00e8.80 (m, 27H, phenanthrenyl H), 8.82 (s, 2H, eCH]N). 13C
0.93 g (72%). Mp: 131e135 ꢁC. FT-IR (
n
/cmꢀ1): 3426 (b), 3053 (m),
NMR (125 MHz,
d/ppm): 136.89, 136.77, 131.18, 130.67, 130.34,
2928 (m), 1686 (s), 1620 (m), 1527 (s), 1252 (s), 1155 (s), 961 (s), 727
129.65, 128.82, 128.07, 126.9, 126.84, 126.45, 125.14, 122.89, 122.22,
(s), 595 (s). 1H NMR (400 MHz,
d
/ppm): 3.61 (d, 3H, eNCH3,
32.34. 31P{1H} NMR (202.5 MHz,
d/ppm): 75.20 (s). Anal. Calcd for
3J(1He31P)¼10 Hz), 7.18e9.07 (m, 19H, phenanthrenyl/phenyl H),
C48H39N6SP from ESIeHRMS (m/z): [4cþH]þ¼calculated 763.2773,
9.46 (s, 1H, eCH]N). 13C NMR (125 MHz,
d/ppm): 131.82, 131.69,
found 763.2775.
131.00, 129.75, 128.40, 127.35, 124.03, 125.72, 123.13, 122.70, 33.61.
Compound 5a: Pyrene-1-carboxaldehyde (0.690 g, 3.00 mmol);
{P(O)[N(Me)NH2]3} (0.182 g, 1.00 mmol). Yield: 0.605 g (74%). Mp:
31P{1H} NMR (202.5 MHz,
d/ppm): 30.82 (s). Anal. Calcd for
C28H23N2O3P from ESIeHRMS (m/z): [2cþH]þ¼calculated 435.1626,
130 ꢁC (d). FT-IR ( /cmꢀ1): 3437 (b), 3037 (m), 2925 (m), 1677 (s),
n
found 435.1626.
1626 (s), 1595 (s), 1463 (s), 1412 (s), 1381 (s), 1268 (s), 1178 (s), 1148
Compound 2d: 7-diethylamino-coumarin-3-aldehyde (0.736 g,
4.23 mmol); {Ph2P(O)[N(Me)eNH2]} (1.042 g, 4.23 mmol). Yield:
(s), 1058 (s), 961 (s). 1H NMR (400 MHz,
d/ppm): 3.51 (d, 3H, eNCH3,
3J(1He31P)¼9.2 Hz), 7.25e9.44 (m, 27H, pyrenyl H), 9.92 (s, 1H,
1.5 g (72%). Mp: 205 ꢁC. FT-IR (
n
/cmꢀ1): 3422 (b), 3056 (m), 2967
eCH]N). 13C NMR (100 MHz,
d/ppm): 130.57, 128.55, 128.00,
(m), 2928 (m), 1971 (s), 1700 (s), 1620 (s), 1518 (s), 1469 (s), 1377 (s),
127.85, 127.35, 125.82, 125.33, 125.03, 124.87, 44.38. 31P{1H} NMR
1226 (s), 1134 (s), 955 (s), 906 (s), 799 (s). 1H NMR (500 MHz,
(202.5 MHz, d/ppm): 16.36 (s). Anal. Calcd for C54H39N6OP from
d
/ppm): 1.15 (t, 6H, eCH3), 3.22 (s, 3H, eNCH3, 3J(1He31P)¼9.0 Hz),
ESIeHRMS (m/z): [5aþH]þ¼calculated 819.3001, found 819.3001.
Compound 5b: Anthracene-9-carboxaldehyde (0.618 g,
3.00 mmol); {P(O)[N(Me)NH2]3} (0.182 g, 1.00 mmol). Yield: 0.60 g
3.42 (q, 4H, eCH2), 6.5 (s, 1H, aromatic H), 6.6 (d, 1H, aromatic H),
7.1e7.6 (m, 10H, aromatic H), 7.82 (s, 1H, eCH]N). 13C NMR
(125 MHz,
d
/ppm): 136.79, 132.39, 132.31, 131.99, 128.33, 128.22,
(80%). Mp: 220e222 ꢁC. FT-IR ( /cmꢀ1): 3419 (b), 3048 (m), 2924
n
44.88, 31.01, 12.44. 31P{1H} NMR (202.5 MHz,
d
/ppm): 32.38 (s).
(m), 1622 (s), 1516 (s), 1463 (s), 1443 (s), 1308 (s), 1019 (s), 1494 (s),

V. Chandrasekhar et al. / Tetrahedron 67 (2011) 6917e6926
6925
1447 (s), 966 (s), 732 (s), 601 (s). 1H NMR (500 MHz,
d
/ppm): 3.57 (d,
129.42, 127.85, 127.43, 125.77, 125.21, 124.95, 122.98, 32.54. 31P{1H}
9H, eNCH3, 3J(1He31P)¼7.5 Hz), 6.70e8.26 (m, 27H, anthracenyl H),
NMR (202.5 MHz,
d
/ppm)¼19.9 (d, 2P, P(N(Me)eN]CHeR)),
8.41 (s, 3H, eCH]N). 13C NMR (125 MHz,
d
/ppm): 135.96, 135.83,
26.8 (t, 1P, P(O2C12H8), 3J(PeNeP)¼65.4 Hz). Anal. Calcd for
C60H42N7O4P3 from ESIeHRMS (m/z): [7aþH]þ¼calculated
1348.4223, found 1348.4226.
131.2, 129.76, 128.34, 127.83, 127.45, 125.73, 125.11, 124.9, 32.43. 31P
{1H} NMR (202.5 MHz,
d/ppm): 16.45 (s). Anal. Calcd for
C48H39N6OP from ESIeHRMS (m/z): [5bþH]þ¼calculated 747.3001,
found 747.3003; [5bþCH3OHþCH3CNþH]þ¼calculated 820.3523,
found 820.3882.
Compound 7b: Anthracene-9-carboxaldehyde (0.824 g,
4.00 mmol); {N3P3(O2C12H8)[N(Me)eNH2]4} (0.701 g, 1.00 mmol).
Yield: 0.813 g (65%). Mp: 220 ꢁC. FT-IR ( /cmꢀ1): 3425 (b), 3048 (m),
n
Compound 5c: Phenanthrene-9-carboxaldehyde (0.618 g,
3.00 mmol); {P(O)[N(Me)NH2]3} (0.182 g, 1.00 mmol). Yield: 0.537 g
1621 (s), 1440 (s), 1222 (s), 1176 (s), 1177 (s), 963 (s), 881 (s), 732 (s).
1H NMR (500 MHz,
d
/ppm): 3.63 (d, 12H, eNCH3, 3J(1He31P)¼
(72%). Mp: 138e140 ꢁC. FT-IR (
n
/cmꢀ1): 3444 (b), 2927 (m), 1618
10.0 Hz), 7.09e8.55 (m, 44H, anthracenyl/phenyl H), 9.59 (s, 4H,
(m), 1447 (s), 1253 (s), 1150 (s), 965.57 (s), 746 (s), 722s. 1H NMR
eCH]N). 13C NMR (125 MHz,
130.02, 129.65, 129.33, 128.58, 128.05, 126.04, 125.82, 125.10, 32.74.
d/ppm): 148.96, 135.61, 131.48,
(500 MHz,
d
/ppm): 3.51 (d, 9H, eNCH3, 3J(1He31P)¼10.0 Hz),
6.99e8.79 (m, 27H, phenanthrenyl H), 8.80 (s, 3H, eCH]N). 13C
31P{1H} NMR (202.5 MHz,
d/ppm): 18.5 (d, 2P, P(N(Me)eN]
NMR (125 MHz
d/ppm): 137.015, 136.89, 131.158, 130.653, 130.357,
CHeR)), 26.0 (t, 1P, P(O2C12H8), 3J(PeNeP)¼70.9 Hz). Anal. Calcd for
C76H60N11O2P3 from ESIeHRMS (m/z): [7bþH]þ¼calculated
1252.4223, found 1252.4221.
129.508, 128.859, 128.154, 126.947, 126.475, 125.035, 122.89,
122.211, 31.988. 31P{1H} NMR (202.5 MHz,
d/ppm): 16.8 (s). Anal.
Calcd for C48H39N6OP from ESIeHRMS (m/z): [5cþH]þ¼calculated
747.3001, found 747.3004; [5cþCH3OHþCH3CNþH]þ¼calculated
820.3523, found 820.3919.
Compound 7c: Phenanthrene-9-carboxaldehyde (0.824 g,
4.00 mmol); {N3P3(O2C12H8)[N(Me)eNH2]4} (0.701 g, 1.00 mmol).
Yield: 0.876 g (70%). Mp: 165e168 ꢁC. FT-IR ( /cmꢀ1): 3448 (b),
n
Compound 6a: Pyrene-1-carboxaldehyde (0.460 g, 2.00 mmol);
{N3P3(O2C12H8)2[N(Me)NH2]2} (0.593 g, 1.00 mmol). Yield: 0.712 g
3060 (m), 2927 (m), 1685 (s), 1614 (s), 1496 (s), 1442 (s), 1222 (s),
1176 (s), 1094 (s), 1042 (s), 964 (s), 748 (s). 1H NMR (500 MHz,
d/
(70%). Mp: 240 ꢁC (d). FT-IR (
n
/cmꢀ1): 3446 (b), 3038 (m), 2925 (m),
ppm): 3.53 (d, 12H, eNCH3, 3J(1He31P)¼8.8 Hz), 7.20e8.83 (m, 44H,
1600 (s), 1501 (s), 1475 (s), 1438 (s), 1382 (s), 1263 (s), 1229 (s), 1093
phenanthrenyl/phenyl H), 8.84 (s, 4H, eCH]N). 13C NMR (125 MHz,
(s), 967 (s). 1H NMR (400 MHz,
d
/ppm): 3.63 (d, 3H, eNCH3,
d
/ppm): 148.75, 136.57, 131.36, 130.58, 130.33, 129.72, 129.62,
3J(1He31P)¼4.8 Hz), 7.25e8.70 (m, 34H, pyrenyl/phenyl H), 8.73 (s,
127.60, 126.88, 126.8, 126.57, 125.42, 122.81, 122.36, 32.22. 31P{1H}
1H, eCH]N). 13C NMR (100 MHz,
d
/ppm): 129.58, 129.08, 127.5,
NMR (202.5 MHz, d/ppm): 19.7 (d, 2P, P(N(Me)eN]CHeR)), 26.6 (t,
125.87, 125.29, 124.98, 123.04, 122.12. 34.11. 31P{1H} NMR
1P, P(O2C12H8), 3J(PeNeP)¼70.9 Hz). Anal. Calcd for C76H60N11O2P3
from ESIeHRMS (m/z): [7cþH]þ¼calculated 1252.4223, found
1252.4221.
(202.5 MHz, d/ppm): 19.8 (t, 1P, P(N(Me)eN]CHeR)), 26.6 (d, 2P,
P(O2C12H8), 3J(PeNeP)¼70.9 Hz). Anal. Calcd for C60H42N7O4P3
from ESIeHRMS (m/z): [6aþH]þ¼calculated 1018.2589, found
1018.2587; [6aþNa]þ¼calculated 1040.2409, found 1040.2274.
Compound 6b: Anthracene-9-carboxaldehyde (0.412 g,
2.00 mmol); {N3P3(O2C12H8)2[N(Me)NH2]2} (0.593 g, 1.00 mmol).
Compound 7d: 7-diethylamino-coumarin-3-aldehyde (0.500 g,
2.874 mmol); {N3P3(O2C12H8)[N(Me)eNH2]4} (0.359 g, 0.71 mmol).
Yield: 0.630 g (63%). Mp: 182e186 ꢁC. FT-IR ( /cmꢀ1): 3423 (b),
n
2971 (m), 2928 (m), 1712 (s), 1608 (s), 1518 (s), 1468 (s), 1354 (s),
Yield: 0.66 g (69%). Mp: 182e184 ꢁC. FT-IR (
(m), 1672 (s), 1439 (s), 1283 (s), 1171 (s), 1092 (s), 964 (s), 878 (s),
n
/cmꢀ1): 3446 (b), 2924
1258 (s), 1132 (m), 964 (s), 907 (s), 741 (s). 1H NMR (400 MHz,
d/
ppm): 1.14 (t, 24H, eCH3), 3.33 (q, 8H (broad), eCH2), 3.25 (s, 12H,
eNCH3, 3J(1He31P)¼8.0 Hz), 6.40 (s, 4H, aromatic H), 6.45 (m, 4H,
aromatic H) 7.1e7.47 (m, 16H, aromatic H), 7.72 (s, 2H, eCH), 8.1 (s,
732 (s). 1H NMR (500 MHz,
d/ppm): 3.63 (d, 6H, eNCH3,
3J(1He31P)¼9.0 Hz), 7.12e8.97 (m, 34H, anthracenyl/phenyl H), 8.98
(s, 2H, eCH]N). 13C NMR (125 MHz,
d
/ppm): 148.56, 135.35, 134.21,
2H, eCH]N). 13C NMR (125 MHz,
d
/ppm): 162.47, 156.21, 150.57,
132.23,130.05,129.38,128.24,127.30,125.93,125.75,123.63,122.12,
137.06, 129.86, 115.42, 109.31, 97.08, 44.83, 32.27, 12.45. 31P{1H}
32.72. 31P{1H} NMR (202.5 MHz,
d
/ppm): 19.0 (t, 1P, P(N(Me)eN]
NMR (202.5 MHz, d/ppm): 20.2 (d, 2P, P(N(Me)eN]CHeR)),
CHeR)), 26.4 (d, 2P, P(O2C12H8), 3J(PeNeP)¼70.9 Hz). Anal. Calcd
for C56H42N7O4P3 from ESIeHRMS: m/z: [6bþH]þ¼calculated
970.2589, found 970.2585.
26.7 (t, 1P, P(O2C12H8), 3J(PeNeP)¼65.4 Hz). Anal. Calcd for
C72H80N15O10P3 from ESIeHRMS (m/z): [7dþH]þ¼calculated
1408.5504, found 1408.5507; [7dþNa]þ¼calculated 1430.5323,
found 1430.5186.
Compound 6c: Phenanthrene-9-carboxaldehyde (0.412 g,
2.00 mmol); {N3P3(O2C12H8)2[N(Me)NH2]2} (0.593 g, 1.00 mmol).
Compound 8b: Anthracene-9-carboxaldehyde (1.236 g,
6.00 mmol); {N3P3[N(Me)NH2]6} (0.701 g, 1.00 mmol). Yield:
Yield: 0.581 g (60%). Mp: 175e178 ꢁC. FT-IR ( /cmꢀ1): 3447 (b),
n
2926 (m), 1618 (m), 1475 (s), 1438 (s), 1264 (s), 1228 (s), 1171 (s),
0.920 g (60%). M.pt.: 132e134 ꢁC. FT-IR ( /cmꢀ1): 3430 (b), 2924
n
1093 (s), 967 (s), 916 (s), 782 (s). 1H NMR (500 MHz,
d
/ppm): 3.48 (d,
(m), 1668 (s), 1443 (s), 1207 (s), 1149 (s), 965 (s), 882 (s), 731 (s), 598
6H, eNCH3, 3J(1He31P)¼9.5 Hz), 7.17e8.70 (m, 34H, phenanthrenyl/
(s). 1H NMR (500 MHz,
d
/ppm): 3.67 (d, 18H, eNCH3, 3J(1He31P)¼
phenyl H), 8.72 (s, 2H, eCH]N). 13C NMR (125 MHz,
d
/ppm):
6.5 Hz), 7.06e8.94 (m, 54H, anthracenyl H), 8.96 (s, 6H, eCH]N).
148.44, 137.04, 136.91, 131.95, 130.62, 129.83, 129.67, 127.75, 126.90,
13C NMR (125 MHz,
129.20, 128.55, 128.33, 127.76, 126.04, 125.85, 125.12, 123.60, 32.93.
d/ppm): 135.33, 132.21, 131.49, 130.01, 129.36,
126.39, 125.84, 125.36, 122.88, 122.4, 122.07, 32.23. 31P{1H} NMR
(202.5 MHz,
d
/ppm): 19.8 (t, 1P, P(N(Me)eN]CHeR)), 26.6 (d, 2P,
31P{1H} NMR (202.5 MHz,
d/ppm): 17.3068 (s). Anal. Calcd for
P(O2C12H8), 3J(PeNeP)¼70.9 Hz). Anal. Calcd for C56H42N7O4P3
from ESIeHRMS (m/z): [6cþH]þ¼calculated 970.2589, found
970.2587; [5bþCH3OHþCH3CNþH]þ¼calculated 1043.3117, found
1043.3539.
C96H78N15P3 from ESIeHRMS (m/z): [8bþH]þ¼calculated
1535.5856, found 1535.5934.
Compound 8c: Phenanthrene-9-carboxaldehyde (1.236 g,
6.00 mmol); {N3P3[N(Me)NH2]6} (0.701 g, 1.00 mmol). Yield:
Compound 7a: Pyrene-1-carboxaldehyde (0.92 g, 4.00 mmol);
{N3P3(O2C12H8)[N(Me)eNH2]4} (0.701 g, 1.00 mmol). Yield: 0.916 g
0.981 g (64%). Mp: 152e155 ꢁC. FT-IR ( /cmꢀ1): 3448 (b), 3055 (m),
n
2925 (m),1566 (m),1493 (s) 1448 (s),1248 (s),1203 (s),1152 (s), 967
(68%). Mp: 158e160 ꢁC. FT-IR (
n
/cmꢀ1): 3449 (b), 3037 (m), 2924
(s), 747 (s). 1H NMR (500 MHz,
d/ppm): 3.61 (d, 18H, eNCH3,
(m), 1675 (s), 1596 (s), 1463 (s), 1438 (s), 1380 (s), 1222 (s), 1176 (s),
3J(1He31P)¼30.0 Hz), 7.23e8.81 (m, 54H, phenanthrenyl H), 8.83 (s,
1094 (s), 961 (s). 1H NMR (400 MHz,
d
/ppm): 3.57 (d, 3H, eNCH3,
6H, eCH]N). 13C NMR (125 MHz,
d/ppm): 141.30, 136.08, 131.43,
3J(1He31P)¼8.56 Hz), 7.24e8.77 (m, 42H, pyrenyl/phenyl H), 9.42 (s,
130.60, 130.18, 129.79, 129.01, 127.26, 126.83, 126.34, 125.93, 125.34,
2H, eCH]N). 13C NMR (100 MHz,
d/ppm): 135.76, 131.33, 130.66,
122.84, 122.72, 32.43. 31P{1H} NMR (202.5 MHz,
d
/ppm): 18.92 (s).

6926
V. Chandrasekhar et al. / Tetrahedron 67 (2011) 6917e6926
Anal. Calcd for C96H78N15P3; ESIeHRMS (m/z): [MþH]þ¼calculated
3927; (d) Kumar, S. S.; Roesky, H. W.; Andronesi, O.; Baldus, M.; Winter, R. F.
Inorg. Chim. Acta 2005, 358, 2349.
5. Chandrasekhar, V.; Andavan, G. T. S.; Nagendran, S.; Krishnan, V.; Azhakar, R.;
1535.5856, found 1535.5935.
Butcher, R. J. Organometallics 2003, 22, 976.
6. (a) Majoral, J. P.; Badri, M.; Caminade, A. M.; Delmas, M.; Gaset, A. Inorg. Chem.
1988, 27, 3873; (b) Mitjaville, J.; Caminade, A. M.; Majoral, J. P. Chem. Commun.
1994, 2161; (c) Caminade, A. M.; Majoral, J. P. Chem. Rev. 1994, 94, 1183; (d)
Mitjaville, J.; Caminade, A. M.; Daran, J. C.; Donnadieu, B.; Majoral, J. P. J. Am.
Chem. Soc. 1995, 117, 1712; (e) Galliot, C.; Caminade, A. M.; Dahan, F.; Majoral, J.
P. Angew. Chem., Int. Ed. Engl. 1993, 32, 1477; (f) Brauge, L.; Magro, G.; Caminade,
A. M.; Majoral, J. P. J. Am. Chem. Soc. 2001, 123, 6698; (g) Slany, M.; Caminade, A.
M.; Majoral, J. P. Tetrahedron Lett. 1996, 37, 9053; (h) Mongin, O.; Krishna, T. R.;
Werts, M. H. V.; Caminade, A. M.; Majoral, J. P.; Blanchard-Desce, M. Chem.
Commun. 2006, 915.
7. (a) Katti, K. V.; Reddy, V. S.; Singh, P. R. Chem. Soc. Rev. 1995, 24, 97; (b) Wang,
M.; Volkert, E. W.; Singh, P. R.; Katti, K. K.; Lusiak, P.; Katti, K. V.; Barnes, C. L.
Inorg. Chem. 1994, 33, 1184; (c) Singh, P. R.; Jimenez, H.; Katti, K. V.; Volkert, W.
A.; Barnes, C. L. Inorg. Chem. 1994, 33, 736; (d) Reddy, V. S.; Katti, K. V.; Barnes,
C. L. Organometallics 1994, 13, 2391.
Acknowledgements
We thank the Department of Science and Technology (DST),
India for financial support. V.C. and M.D.P. are thankful to the De-
partment of Science and Technology for a J.C. Bose National fel-
lowship and DST-SERC Fast Track Scheme for Young Scientists
Fellowship, respectively. B.M. thankful to CSIR, New Delhi, India for
a Senior Research Fellowship. This work is also supported by the
Bioinorganic Chemistry Initiative, DST, India.
Supplementary data
8. (a) Chandrasekhar, V.; Pandian, B. M. Acc. Chem. Res. 2009, 42, 1047; (b)
Scanned images of 31P{1H} NMR and ESIeHRMS spectra. CCDC
809367 (1b), 809368 (2b), 809369 (3b), 809370 (4b), 809371 (5b),
809372 (5c) and 806357 (6d) contain the supplementary crystal-
lographic data for this paper. These data can be obtained free of
charge at www.ccdc.cam.ac.uk/conts/retrieving.html [or from the
Cambridge Crystallographic Data Centre, 12, Union Road, Cam-
bridge CB2 1EZ, UK; fax: þ44 1223/336 033; e-mail: depos-
it@ccdc.cam.ac.uk]. Supplementary data associated with this article
can be found in online version at doi:10.1016/j.tet.2011.06.073.
Chandrasekhar, V.; Azhakar, R.; Andavan, G. T. S.; Krishnan, V.; Zacchini, S.;
€
Bickley, J. F.; Steiner, A.; Butcher, R. J.; Kogerler, P. Inorg. Chem. 2003, 42, 5989;
(c) Chandrasekhar, V.; Andavan, G. T. S.; Azhakar, R.; Pandian, B. M. Inorg. Chem.
2008, 47, 1922; (d) Chandrasekhar, V.; Azhakar, R.; Pandian, B. M.; Bickley, J. F.;
Steiner, A. Eur. J. Inorg. Chem. 2008, 7, 1116; (e) Chandrasekhar, V.; Pandian, B.;
ꢁ
Azhakar, R.; Boomishankar, R.; Steiner, A.; Vittal, J. J.; Houri, A.; Clecrac, R. Inorg.
ꢁ
Chem. 2008, 47, 4918; (f) Chandrasekhar, V.; Pandian, B. M.; Vittal, J. J.; Clecrac,
R. Inorg. Chem. 2009, 48, 1148; (g) Chandrasekhar, V.; Azhakar, R.; Murgesa-
pandian, B.; Senapati, T.; Bag, P.; Pandey, M. D.; Maurya, S. K.; Goswami, D.
Inorg. Chem. 2010, 49, 4008; (h) Chandrasekhar, V.; Pandey, M. D.; Gopal, K.;
Azhakar, R. Dalton Trans. doi:10.1039/c1dt10294j
9. (a) Chandrasekhar, V.; Pandey, M. D.; Bag, P.; Pandey, S. Tetrahedron 2009, 65,
4540; (b) Chandrasekhar, V.; Bag, P.; Pandey, M. D. Tetrahedron 2009, 65, 9876;
(c) Chandrasekhar, V.; Pandey, M. D.; Das, B.; Mahanti, B.; Senapati, T. Indian J.
Chem., Sect. A 2011, 50A, 453.
References and notes
10. Vilkov, L. V.; Sadova, N. I.; Zilberg, I. Y. Zh. Strukt. Khim. 1967, 8, 528.
11. Wingerter, S.; Pfeiffer, M.; Murso, A.; Lustig, C.; Stey, T.; Chandrasekhar, V.;
Stalke, D. J. Am. Chem. Soc. 2001, 123, 1381.
12. Chandrasekhar, V.; Justin Thomas, K. R. Struct. Bonding 1993, 81, 41.
13. Mani, N. V.; Ahmad, F. R.; Barnes, W. H. Acta Crystallogr. 1965, 19, 693.
14. (a) Behera, K.; Pandey, M. D.; Porel, M.; Pandey, S. J. Chem. Phys. 2007, 127,
184501; (b) Chandrasekhar, V.; Kumar, A.; Pandey, M. D. J. Organomet. Chem.
2010, 695, 74; (c) Pandey, M. D.; Mishra, A. K.; Chandrasekhar, V.; Verma, S.
Inorg. Chem. 2010, 49, 2020.
€
1. (a) Schneider, R.; Kollner, C.; Weber, I.; Togni, A. Chem. Commun. 1999, 2415; (b)
Chandrasekhar, V.; Nagendran, S. Chem. Soc. Rev. 2001, 30, 193; (c) Koprowski,
M.; Sebastian, R. M.; Maraval, V.; Zablocka, M.; Cadierno, V.; Donnadieu, B.;
Igau, A.; Caminade, A. M.; Majoral, J. P. Organometallics 2002, 21, 4680; (d)
Darcos, V.; Dureault, A.; Taton, D.; Gnanou, Y.; Marchand, P.; Caminade, A.;
Majoral, J. P.; Destarac, M.; Leising, F. Chem. Commun. 2004, 2110.
2. (a) Kim, C.; Jeong, Y.; Jung, I. J. Organomet. Chem. 1998, 9, 570; (b) Casado, C. M.;
Cuadrado, I.; Moran, M.; Alonso; Barranco, M.; Losada, J. Appl. Organomet. Chem.
ꢁ
ꢁ
ꢁ
15. (a) Carriedo, G. A.; Fernndez-Catuxo, L.; Alonso, F. J. G.; Gmez-Elipe, P.; Gonzlez,
P. A. Macromolecules 1996, 29, 5320; (b) Majoral, J. P.; Kraemer, R.; Navech, J.;
Mathias, F. Tetrahedron 1976, 32, 2633.
16. (a) Ray, D.; Bharadwaj, K. P. Inorg. Chem. 2008, 47, 2252; (b) Wu, J.-S.; Liu, W.-
M.; Zhuang, X.-Q.; Wang, F.; Wang, P.-F.; Tao, S.-L.; Zhang, X.-H.; Wu, S.-K.; Lee,
S.-T. Org. Lett. 2007, 9, 33.
1999, 13, 245; (c) Murfee, H. J.; Thoms, T. P. S.; Greaves, J.; Hong, B. Inorg. Chem.
2000, 39, 5209; (d) Ropartz, L.; Morris, R. E.; Cole-Hamilton, D. J.; Foster, D. F.
Chem. Commun. 2001, 361; (e) Ropartz, L.; Foster, D. F.; Morris, R. E.; Slawin, A.
M. Z.; Cole-Hamilton, D. J. J. Chem. Soc., Dalton Trans. 2002, 1997.
3. (a) Kotz, J. C.; Painter, W. J. J. Organomet. Chem. 1971, 32, 231; (b) Gates, D. P.;
McWilliams, A. R.; Ziembinski, R.; Liable-Sands, L. M.; Guzei, I. A.; Yap, G. P. A.;
Rheingold, A. L.; Manners, I. Chem.dEur. J. 1998, 4, 1497; (c) Bats, J. W.; Ma, K.;
Wagner, M. Acta Crystallogr. 2002, C58, m129; (d) Lerner, H. W.; Scholz, S.; Bats,
J. W.; Bolte, M.; Wagner, M. J. Organomet. Chem. 2002, 664, 94.
4. (a) Stasch, A.; Ferbinteanu, M.; Prust, J.; Zheng, W.; Cimpoesu, F.; Magull, J.;
Schmidt, H. G.; Noltemeyer, M. J. Am. Chem. Soc. 2002, 124, 5441; (b) Kumar, S.
S.; Reddy, N. D.; Roesky, H. W.; Vidovic, D.; Magull, J.; Winter, R. F. Organo-
metallics 2003, 22, 3348; (c) Kumar, S. S.; Roesky, H. W. Dalton Trans. 2004,
17. (a) Dawson, W. R.; Windsor, M. W. J. Phys. Chem. 1968, 72, 3251; (b) Paeker, C. A.;
Ress, W. T. Analyst 1960, 85, 587.
18. (a) SMART and SAINT Software Reference Manuals (Ver. 6.45); Bruker Analytical
X-ray Systems: Madison, WI, 2003; (b) Sheldrick, G. M. SADABS: a Software for
Empirical Absorption Correction (Ver. 2.05); University of Gottingen: Gottingen,
Germany, 2002; (c) Sheldrick, G. M. SHELXTL (Ver. 6.12); Bruker AXS: Madison,
WI, 2001.