Divergent topologies in luminescent zinc and cadmium substituted isophthalate coordination polymers constructed from long-spanning dipyridylamide ligand precursors

Article abstract of DOI:10.1016/j.ica.2017.08.024

Hydrothermal reaction of zinc or cadmium nitrate, a 5-position substituted isophthalic acid, and the long-spanning dipyridylamide ligand N,N′-(hexane-1,6-diyl)dinicotinamide (hdn) resulted in coordination polymers whose dimensionalities depend on the nature of the ring substituent and the metal coordination environment. The six new phases were characterized by single crystal X-ray diffraction. {[Zn₂(hip)₂(H₂O)₂(hdn)]·2H₂O}_n (1, hip = 5-hydroxyisophthalate) shows a 1D ladder topology with [Zn(hip)(H₂O)]_n uprights spanned by disordered hdn rungs. {[Zn₂(nip)₂(hdn)₂]·2H₂O}_n (2, nip = 5-nitroisophthalate) displays a 1D ribbon motif with [Zn(nip)]_n chains pillared by looped pairs of hdn ligands. [Zn₃(tbip)₂(nic)₂]_n (3, tbip = 5-tert-butylisophthalate, nic = nicotinate) shows trimeric [Zn₃(OCO)₂] clusters connected into a 3D 8-connected 4²⁴6⁴ bcu net by tbip and in situ generated nic ligands. {[Cd₂(ip)₂(H₂O)₄(hdn)]·2H₂O}_n (4, ip = isophthalate) and {[Cd₂(tbip)₂(H₂O)₄(hdn)]·H₂O}_n (5) both show a ladder topology similar to that in 1. {[Cd(mip)(hdn)]·H₂O}_n (6, mip = 5-methylisophthalate) manifests a 2D (4,4) grid topology based on linked dimeric [Cd₂(OCO)₂] units. Luminescent properties were probed; compounds 4 and 6 showed good ability to detect nitrobenzene in ethanol suspension.

Full text of DOI:10.1016/j.ica.2017.08.024

Accepted Manuscript
Divergent topologies in luminescent zinc and cadmium substituted isophthalate
coordination polymers constructed from long-spanning dipyridylamide ligand
precursors
Abigail E. Meyers, Renee K. Randolph, Robert L. LaDuca
PII:
S0020-1693(17)31080-0
http://dx.doi.org/10.1016/j.ica.2017.08.024
ICA 17818
DOI:
Reference:
Inorganica Chimica Acta
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Accepted Date:
10 July 2017
8 August 2017
11 August 2017
Please cite this article as: A.E. Meyers, R.K. Randolph, R.L. LaDuca, Divergent topologies in luminescent zinc and
cadmium substituted isophthalate coordination polymers constructed from long-spanning dipyridylamide ligand
precursors, Inorganica Chimica Acta (2017), doi: http://dx.doi.org/10.1016/j.ica.2017.08.024
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Divergent topologies in luminescent zinc and cadmium substituted isophthalate coordination
polymers constructed from long-spanning dipyridylamide ligand precursors
Abigail E. Meyers, Renee K. Randolph, and Robert L. LaDuca*
Lyman Briggs College and Department of Chemistry
Michigan State University, East Lansing, MI 48825 USA
Keywords: crystal structure; coordination polymer; zinc; luminescence; nitrobenzene detection

Abstract
Hydrothermal reaction of zinc or cadmium nitrate, a 5-position substituted isophthalic acid, and
the long-spanning dipyridylamide ligand N,N-(hexane-1,6-diyl)dinicotinamide (hdn) resulted in
coordination polymers whose dimensionalities depend on the nature of the ring substituent and
the metal coordination environment. The six new phases were characterized by single crystal X-
ray diffraction. {[Zn2(hip)2(H2O)2(hdn)]·2H2O}n (1, hip = 5-hydroxyisophthalate) shows a 1D
ladder topology with [Zn(hip)(H2O)]n uprights spanned by disordered hdn rungs.
{[Zn2(nip)2(hdn)2]·2H2O}n (2, nip = 5-nitroisophthalate) displays a 1D ribbon motif with
[Zn(nip)]n chains pillared by looped pairs of hdn ligands. [Zn3(tbip)2(nic)2]n (3, tbip = 5-tert-
butylisophthalate, nic = nicotinate) shows trimeric [Zn3(OCO)2] clusters connected into a 3D 8-
connected 42464 bcu net by tbip and in situ generated nic ligands.
{[Cd2(ip)2(H2O)4(hdn)]·2H2O}n (4, ip = isophthalate) and {[Cd2(tbip)2(H2O)4(hdn)]·H2O}n (5)
both show a ladder topology similar to that in 1. {[Cd(mip)(hdn)]·H2O}n (6, mip = 5-
methylisophthalate) manifests a 2D (4,4) grid topology based on linked dimeric [Cd2(OCO)2]
units. Luminescent properties were probed; compounds 4 and 6 showed good ability to detect
nitrobenzene in ethanol suspension.

1. Introduction
Academic and industrial research into the synthesis and property characterization of
divalent metal coordination polymers has continued largely unabated over the past ten years.
This genre of materials can exhibit remarkable multifunctional properties in diverse applications
such as gas storage [1], selective separations [2], pharmaceutical delivery [3], and industrially
relevant heterogeneous catalysis [4]. The undeniable aesthetic appeal of their molecular-level
structures and topologies also spurs continued study [5], with exploratory synthesis playing an
inordinately large role in the uncovering of new entangled or interpenetrated topologies because
of the difficulty of strictly a priori structure design [6]. Many coordination polymer solids are
self-assembled under hydrothermal or solvothermal conditions from divalent metal salts and
simple aromatic dicarboxylate ligands such as isophthalate (ip, Scheme 1) [7] or terephthalate
(tp) [8]. Inclusion of dipyridyl-type coligands such as the rigid-rod linker 4,4-bipyridine (bpy)
can influence the structural topology and resulting functional properties. For instance, the
apohost of {[Zn2(tp)2(bpy)]·H2O·DMF}n can separate mixtures of light weight gaseous alkanes
[9]. Some cadmium and zinc aromatic dicarboxylate coordination polymers have recently shown
utility as detectors for nitroaromatic contaminants, via luminescence quenching mechanisms
[10–12].
It has been possible to alter the dimensionalities and topologies of isophthalate-based
coordination polymers by employing dicarboxylate ligands with sterically bulkier substituents on
their aromatic rings. Yang and co-workers identified a trend of lower coordination polymer
dimensionality when 5-position substituted isophthalate derivatives such as 5-tert-
butylisophalate (tbip, Scheme 1) or 5-hydroxyisophthalate (hip, Scheme 1) were employed

during self-assembly in the presence of pyridine capping ligands [13]. In a series of zinc
isophthalate coordination polymers with the longer-spanning coligand bis(4-
pyridylmethyl)piperazine (bpmp), substituent-dependent structural trends were less clear.
[Zn(ip)(bpmp)]n and {[Zn(hip)(bpmp)]·H2O}n both showed a system of five-fold interpenetrated
66 diamondoid nets [14–15]. Even the very bulky tert-butyl group in tbip afforded a 3D topology
in [Zn2(tbip)2(bpmp)]n, although with a shift to a dimer-based two-fold interpenetrated 41263 pcu
topology. {[Zn(meoip)(bpmp)]·8H2O}n adopted an undulating (4,4) single-grid 2-D topology, in
concert with the dimensionality reducing trend identified by Yang. The methyl group in 5-
methylisophthalate (mip, Scheme 1) can also induce significant structural changes.
{[Cd2(ip)2(H2O)2(bpfp)]·7H2O}n and {[Cd(mip)(H2O)(bpfp)]·3H2O}n both display a (4,4) grid
topology, but the former exhibits simple stacked layers while the latter exhibits 2D + 2D  3D
mutual inclined interpenetration [16].
The long-spanning and conformationally flexible dipyridylamide coligand N,N-(hexane-
1,6-diyl)dinicotinamide (hdn, Scheme 2) has infrequently been employed in coordination
polymer chemistry to date, although Wang and co-workers have reported some examples in
recent years [17–19]. Wang’s group prepared the divalent coordination polymer
{[Cu(ip)(hdn)]·H2O}n, which manifested a 3,5 connected 3,5L2 layered topology, and underwent
reversible electrochemical reduction to CuI when admixed with carbon paste [17]. There are no
current reports of 5-position substituted isophthalate zinc- or cadmium-based coordination
polymers containing hdn, although a few years ago Wang’s group reported some copper [18] and
cobalt [19] derivatives containing these ligands. We therefore endeavored to synthesize a series
of divalent zinc and cadmium coordination polymers containing 5-substituted isophthalate
ligands and hdn.

In this contribution we present the single-crystal structures, divergent topological
features, luminescence properties, nitrobenzene detecting capabilities, and thermal degradation
of six new zinc and cadmium coordination polymers with hdn and substituted isophthalate
ligands: {[Zn2(hip)2(H2O)2(hdn)]·2H2O}n (1), {[Zn2(nip)2(hdn)2]·2H2O}n (2), [Zn3(tbip)2(nic)2]n
(3, nic = nicotinate), {[Cd2(ip)2(H2O)4(hdn)]·2H2O}n (4), {[Cd2(tbip)2(H2O)4(hdn)]·H2O}n (5),
and {[Cd(mip)(hdn)]·H2O}n (6).
2. Experimental Section
2.1 General Considerations
Metal nitrates and the dicarboxylic acids were commercially obtained from Sigma
Aldrich. N,N-(hexane-1,6-diyl)dinicotinamide (hdn) was prepared by condensation of 1,6-
hexanediamine and two molar equivalents of nicotinoyl chloride hydrochloride in dry pyridine.
The reaction mixture was quenched with water, and then the product was isolated via CH2Cl2
extraction and removal of solvent in vacuo [20]. Water was deionized above 3MΩ–cm in-house.
IR spectra were recorded on powdered samples using a Perkin Elmer Spectrum One DRIFT
instrument. Thermogravimetric analysis was performed on a TA Instruments Q-50
Thermogravimetric Analyzer with a heating rate of 10 °C/min up to 600 °C. Elemental Analysis
was carried out using a Perkin Elmer 2400 Series II CHNS/O Analyzer. The luminescence
spectra were obtained with a Hitachi F-4500 Fluorescence Spectrometer on solid crystalline
samples anchored to quartz microscope slides with Rexon Corporation RX-22P ultraviolet-
transparent epoxy adhesive.

2.2 Preparation of {[Zn2(hip)2(H2O)2(hdn)]·2H2O}n (1)
Zn(NO3)2·6H2O (83 mg, 0.28 mmol), 5-hydroxyisophthalic acid (51 mg, 0.28 mmol), and hdn
(91 mg, 0.28 mmol), and 0.55 mL of a 1.0 M NaOH solution were mixed with 10 mL of distilled
H2O in a 23 mL Teflon-lined acid digestion bomb. The bomb was sealed and heated in an oven
at 120 °C for 4 d, and then was cooled slowly to 25 °C. Straw-colored crystals of 1 (82 mg, 66 %
yield based on Zn) were isolated after washing with distilled water, ethanol, and acetone and
drying in air. Anal. Calc. for C34H38N4O16Zn2 1: C, 45.91; H, 4.31; N, 6.30 % Found: C, 45.56;
H, 4.51; N, 6.04 %. IR (cm–1): 3712 (w), 3315 (w), 2936 (w), 2860 (w), 2073 (w), 1633 (m),
1608 (w), 1544 (s), 1485 (w), 1459 (w), 1435 (w), 1366 (s), 1319 (w), 1294 (w), 1270 (m), 1210
(m), 1167 (w), 1117 (w), 1102 (w), 1062 (w), 1035 (w), 1025 (w), 978 (w), 935 (w), 890 (w),
825 (w), 814 (w), 776 (m), 739 (m), 655 (m).
2.3 Preparation of {[Zn2(nip)2(hdn)2]·2H2O}n (2)
Zn(NO3)2·6H2O (83 mg, 0.28 mmol), 5-nitroisophthalic acid (59 mg, 0.28 mmol), and hdn (91
mg, 0.28 mmol), and 0.55 mL of a 1.0 M NaOH solution were mixed with 10 mL of distilled
H2O in a 23 mL Teflon-lined acid digestion bomb. The bomb was sealed and heated in an oven
at 120 °C for 5 d, and then was cooled slowly to 25 °C. Colorless crystals of 2 (109 mg, 63 %
yield based on Zn) were isolated after washing with distilled water, ethanol, and acetone and
drying in air. Anal. Calc. for C52H54N10O16Zn2 2: C, 51.80; H, 4.51; N, 11.62 % Found: C,

51.41; H, 4.26; N, 11.10 %. IR (cm–1): 3377 (w, br), 2923 (w), 1634 (m), 1627 (m), 1577 (w),
1542 (m), 1474 (w), 1384 (m), 1344 (s), 1294 (m), 1090 (w), 1083 (w), 934 (w), 836 (m), 765
(m), 734 (s), 702 (s), 652 (m), 615 (m).
2.4 Preparation of [Zn3(tbip)2(nic)2]n (3)
Zn(NO3)2·6H2O (83 mg, 0.28 mmol), 5-tert-butylisophthalic acid (62 mg, 0.28 mmol), and hdn
(91 mg, 0.28 mmol), and 0.55 mL of a 1.0 M NaOH solution were mixed with 10 mL of distilled
H2O in a 23 mL Teflon-lined acid digestion bomb. The bomb was sealed and heated in an oven
at 120 °C for 4 d, and then was cooled slowly to 25 °C. Colorless crystals of 3 (15 mg, 18 %
yield based on Zn) were isolated after washing with distilled water, ethanol, and acetone and
drying in air. Anal. Calc. for C36H32N2O12Zn3 3: C, 49.09; H, 3.66; N, 3.18 % Found: C, 48.79;
H, 3.78; N, 3.28 %. IR (cm–1): 2967 (w), 2563 (w), 1994 (w), 1683 (w), 1603 (w), 1550 (s),
1445 (w), 1409 (w), 1366 (s), 1318 (w), 1277 (w), 1112 (w), 1071 (w), 1013 (w), 947 (w), 912
(w), 855 (w), 781 (w), 759 (w), 727 (w), 694 (w), 687 (w), 662 (w).
2.5 Preparation of {[Cd2(ip)2(H2O)4(hdn)]·2H2O}n (4)
Cd(NO3)2·4H2O (86 mg, 0.28 mmol), isophthalic acid (47 mg, 0.28 mmol), and hdn (91 mg, 0.28
mmol), and 0.55 mL of a 1.0 M NaOH solution were mixed with 10 mL of distilled H2O in a 23
mL Teflon-lined acid digestion bomb. The bomb was sealed and heated in an oven at 120 °C for
4 d, and then was cooled slowly to 25 °C. Colorless crystals of 4 (20 mg, 14 % yield based on
Cd) were isolated after washing with distilled water, ethanol, and acetone and drying in air. Anal.
Calc. for C34H42Cd2N4O16 4: C, 41.35; H, 4.29; N, 5.67 % Found: C, 41.41; H, 4.01; N, 5.39 %.
IR (cm–1): 3008 (w), 2923 (s), 2854 (m), 2149 (w), 2047 (w), 1743 (s), 1656 (m), 1602 (w), 1549
(s), 1464 (m), 1378 (s), 1228 (m), 1160 (s), 1097 (m), 912 (w), 853 (w), 832 (w), 722 (m), 682
(m), 662 (m).

2.6 Preparation of {[Cd2(tbip)2(H2O)4(hdn)]·H2O}n (5)
Cd(NO3)2·4H2O (86 mg, 0.28 mmol), 5-tert-butylisophthalic acid (62 mg, 0.28 mmol), and hdn
(91 mg, 0.28 mmol), and 0.55 mL of a 1.0 M NaOH solution were mixed with 10 mL of distilled
H2O in a 23 mL Teflon-lined acid digestion bomb. The bomb was sealed and heated in an oven
at 120 °C for 4 d, and then was cooled slowly to 25 °C. Colorless crystals of 5 (121 mg, 80 %
yield based on Cd) were isolated after washing with distilled water, ethanol, and acetone and
drying in air. Anal. Calc. for C42H56Cd2N4O15 5: C, 46.63; H, 5.22; N, 5.18 % Found: C, 46.82;
H, 5.10; N, 5.42 %. IR (cm–1): 3277 (w), 2926 (w), 1668 (m), 1644 (m), 1601 (m), 1547 (s),
1475 (m), 1416 (m), 1365 (s), 1310 (m), 1244 (w), 1200 (w), 1115 (w), 1033 (w), 833 (w), 776
(m), 729 (s), 699 (s), 667 (w).
2.7 Preparation of {[Cd(mip)(hdn)]·H2O}n (6)
Cd(NO3)2·4H2O (86 mg, 0.28 mmol), 5-methylisophthalic acid (50 mg, 0.28 mmol), and hdn (91
mg, 0.28 mmol), and 0.55 mL of a 1.0 M NaOH solution were mixed with 10 mL of distilled
H2O in a 23 mL Teflon-lined acid digestion bomb. The bomb was sealed and heated in an oven
at 120 °C for 4 d, and then was cooled slowly to 25 °C. Colorless crystals of 6 (76 mg, 43 %
yield based on Cd) were isolated after washing with distilled water, ethanol, and acetone and
drying in air. Anal. Calc. for C27H30CdN4O7 6 C, 51.07; H, 4.76; N, 8.82 % Found: C, 50.92; H,
4.39; N, 8.68 %. IR (cm–1): 3260 (w), 2927 (w), 2863 (w), 1667 (m), 1641 (m), 1601 (m), 1475
(m), 1546 (s), 1416 (m), 1364 (m), 1306 (m), 1244 (m), 1196 (m), 1115 (m), 1048 (m), 1033
(m), 947 (w), 928 (w), 835 (w), 774 (m), 728 (s), 699 (s).
2.8 Nitrobenzene detection studies

Suspensions of 5 mg finely ground samples of coordination polymers 4 and 6 were made
in 5 mL ethanol in volumetric flasks, with immersion in an ultrasonic bath for 60 seconds to
ensure an even dispersion. The fluorescence spectra of 4 and 6 in suspension were recorded with
an excitation wavelength of 270 nm. Aliquots of a stock solution of nitrobenzene (1  10–4 M) in
dimethyl sulfoxide were added sequentially to the ethanol suspensions of 4 and 6 in quartz
cuvettes with sonication for 30 seconds after each addition. The emission spectra were then
measured after each aliquot of analyte solution.
3. X-ray Crystallography
Diffraction data for 1–6 were collected on a Bruker-AXS SMART-CCD X-ray
diffractometer using graphite-monochromated Mo-Kα radiation (λ= 0.71073 Å) at 173 K. The
data were processed via SAINT [21], and corrected for both Lorentz and polarization effects and
absorption effects using SADABS [22]. The structures were solved using direct methods with
SHELXTL [23] within the OLEX2 crystallographic software suite [24]. All non-hydrogen
atoms were refined anisotropically. Hydrogen atoms were placed in calculated positions and
refined isotropically with a riding model. Crystallographic disorder within the hdn ligands in
some cases and the tert-butyl groups in 5 was successfully modeled with partial occupancies and
separate parts. Crystallographic details for 1–6 are given in Table 1.
4. Results and Discussion
4.1 Synthesis and Spectra

Crystalline samples of 1–6 were produced by the hydrothermal reaction of zinc or cadmium
nitrate, the requisite dicarboxylic acid, and hdn in the presence of aqueous base. The infrared
spectra of 1–6 were consistent with their structural components as determined by single-crystal
X-ray diffraction. Intense, broad asymmetric and symmetric C–O stretching bands within the
carboxylate ligands were observed at 1544 and 1366 cmꢀ1 for 1, 1542 and 1384 cmꢀ1 for 2, at
1550 and 1366 cmꢀ1 for 3, at 1549 and 1378 cmꢀ1 for 4, at 1547 and 1365 cmꢀ1 for 5, and at
1545 and 1364 cmꢀ1 for 6. Moderate intensity bands in the range of ~1600 cmꢀ1 to ~1300 cmꢀ1
are attributed to the stretching modes of the pyridyl rings of the hdn ligands [25]. Features
corresponding to C–H bending and ring puckering within the pyridyl moieties exist in the region
between ~900 and ~650 cmꢀ1. Broad, weak spectral bands in the vicinity of ~3000–3400 cmꢀ1
indicate the presence of bound and unbound water molecules in the spectrum of 1–2 and 4–6.
The carbonyl stretching bands for the hdn ligands appeared at 1633 cmꢀ1 for 1, 1634 cmꢀ1 for 2,
1656 cmꢀ1 for 4, 1668 cmꢀ1 for 5, and 1667 cmꢀ1 for 6.
4.2 Structural description of {[Zn2(hip)2(H2O)2(hdn)]·2H2O}n (1)
The asymmetric unit of compound 1 contains a divalent zinc atom, a fully deprotonated
hip ligand, an aqua ligand, a water molecule of crystallization, and an hdn ligand best refined
with each atom at half-occupancy indicating full ligand disorder across a crystallographic
inversion center. The zinc atom displays a distorted {ZnO3N} tetrahedral coordination
environment (Fig. 1) with the nitrogen atom donor being supplied by the pyridyl ring of the
disordered hdn ligand. Two of the oxygen donors belong to different hip ligands, with the aqua

ligand filling the remaining coordination site. Bond lengths and angles within the coordination
tetrahedron are listed in Table 2.
[Zn(H2O)]2+ coordination fragments are linked into neutral [Zn(hip)(H2O)]n coordination
polymer chains that are oriented along the a crystal direction by bis(monodentate) hip ligands
(Fig. 2a); the Zn···Zn through-ligand distance of 10.093(1) Å matches the a lattice parameter.
Pairs of these chain motifs are pillared into [Zn2(hip)2(H2O)2(hdn)]n 1D coordination polymer
ladders by disordered hdn ligands that serve as the rungs (Fig. 2b). The Zn···Zn internuclear
distance spanned by the hdn ligands measures 16.49(2) Å. Both disordered hdn conformations
show an anti-anti-anti disposition of their central aliphatic chains with four-C atom torsion
angles of 175.5, 177.9, and 178.7°. Close – stacking of the aromatic rings of the hip ligands
(ring centroid-ring centroid = 3.479(3) Å) serves to aggregate neighboring
[Zn2(hip)2(H2O)2(hdn)]n 1D ladder motifs into supramolecular layers coincident with the ac
crystal planes (Fig. 3). In turn the supramolecular layers are aggregated into the full crystal
structure of 1 in an AAA stacking pattern along the b crystal direction (Fig. S1) by hydrogen
bonding donation between the bound water molecules and unligated hip carboxylate oxygen
atoms (Table S1). Unligated water molecules are held in the interlamellar regions by accepting
hydrogen bonding from the hydroxyl substituents of the hip ligands, and donating hydrogen
bonding to the amide carbonyl groups of the hdn ligands.
4.3 Structural description of {[Zn2(nip)2(hdn)2]·2H2O}n (2)
The asymmetric unit of compound 2 contains a divalent zinc atom, a fully deprotonated
nip ligand, an hdn ligand, and a water molecule of crystallization. A distorted {ZnN2O2}
coordination tetrahedron is observed at zinc (Fig. 4a), with pyridyl nitrogen donor atoms from

two hdn ligands and single carboxylate oxygen atom donors from two nip ligands. Bond lengths
and angles within the coordination tetrahedron are listed in Table 3.
Similar to the chain structural motif seen in 1, the zinc atoms are connected into 1D
[Zn(nip)]n coordination polymer chains by bis(monodentate) nip ligands that span Zn···Zn
internuclear distances of 9.580(3) Å (Fig. 4b). These are linked into [Zn2(nip)2(hdn)2]n ribbons
by pairs of hdn ligands that connect Zn atoms at a distance of 16.78(3) Å (Fig. 4c). The hdn
ligands have a splayed-open anti-anti-anti conformation about their central hexamethylene units
with torsion angles of 166.7, 178.1, and 169.9°. The 1D ladder and ribbon topologies of 1 and 2
stand in contrast with the undulating 2D (4,4) grid structure of the previously reported
unsubstituted zinc isophthalate phase {[Zn(ip)(hdn)]·1.5H2O}n [16], corroborating a trend of 5-
position substituents resulting in a decrease in coordination polymer dimensionality. When
viewed down the b crystal direction, incipient small channels within the ribbon motif can be seen
(Fig. 5d); these contain comprise 3.7 % of the unit cell volume, as calculated by PLATON [26],
and contain isolated water molecules of crystallization that engage in hydrogen bonding donation
to hdn carbonyl groups as well as unligated nip carboxylate oxygen atoms (Table S1). Adjacent
ribbon motifs aggregate into supramolecular layers by two different intermolecular interactions.
Hydrogen bonding donation between hdn N–H groups and unligated nip nitro group oxygen
atoms provides the main impetus for aggregation, while close – stacking between aromatic
rings of neighboring nip ligands (centroid-to-centroid distance = 3.472(8) Å) imparts an ancillary
structure directing effect. These supramolecular layers further interact by hydrogen bonding
between hdn N–H groups and hdn carbonyl oxygen atoms, stacking in a direct AAA pattern along
the a crystal direction (Fig. S2).

4.4 Structural description of [Zn3(tbip)2(nic)2]n (3)
The asymmetric unit of compound 3 contains a divalent zinc atom (Zn1) on a
crystallographic inversion center, a divalent zinc atom (Zn2) on a general position, a fully
deprotonated tbip ligand, and a nicotinate (nic) ligand that was generated in situ from amide
hydrolysis of the hdn starting material. A symmetry-enforced {ZnO6} coordination octahedron
is observed at Zn1, with single carboxylate oxygen donor atoms from two nic ligands in the
nominal axial positions. Its nominal equatorial positions are taken up by single carboxylate
oxygen atom donors from four different tbip ligands. On the other hand, Zn2 displays a
{ZnNO3} distorted tetrahedral coordination environment, with the single nitrogen donor atom
part of a nic ligand, a single carboxylate oxygen atom from another nic ligand, and carboxylate
oxygen atom donors from two different tbip ligands (Fig. 5a). Pertinent bond lengths and angles
for 3 are listed in Table 4.
Bridging carboxylate groups from four different tbip ligands and two different nic ligands
construct trinuclear {Zn3(OCO)6} linear cluster units (Fig. 5b), that have Zn1···Zn2 distances of
3.532(1) Å. These are linked by the full span of four tbip ligands to construct [Zn3(tbip)2]n
coordination polymer layers arranged parallel to the (1 0 ) crystal planes (Fig. 6a), here each
trinuclear cluster acts as a 4-connected node in a (4,4) grid topology. The {Zn3(OCO)6} clusters
are also connected by four nic ligands to construct [Zn3(nic)2]n coordination polymer layers
oriented parallel to the (1 0 1) crystal planes (Fig. 6b), orthogonally situated to the [Zn3(tbip)2]n
layer motifs. Both sets of layer patterns intersect to afford a 3D [Zn3(tbip)2(nic)2]n coordination
polymer network (Fig. 7); if the {Zn3(OCO)6} clusters are considered 8-connected nodes, a 42464
bcu body-centered cubic topology can be invoked (Fig. 8), as calculated by TOPOS [27]. The

lack of any incipient void space in the 3D network of 3 prevents the occlusion of any co-
crystallized species.
4.5 Structural description of {[Cd2(ip)2(H2O)4(hdn)]·2H2O}n (4)
The asymmetric unit of compound 4 contains a divalent cadmium atom, a fully deprotonated,
unsubstituted ip ligand, two aqua ligands, a water molecule of crystallization, and half of an hdn
ligand. The cadmium atom exhibits a distorted {CdO6N} pentagonal bipyramidal coordination
environment (Fig. 9a) with bound water molecules in the axial positions. The equatorial plane
consists of chelating carboxylate groups from two ip ligands and a pyridyl nitrogen donor atom
from an hdn ligand. Bond lengths and angles within the coordination environment are given in
Table 5.
[Cd(H2O)2]2+ cationic coordination fragments are conjoined into neutral [Cd(ip)(H2O)2]n
coordination polymer chain motifs that are oriented parallel to the a crystal direction by
bis(chelating) ip ligands with a Cd···Cd through-ligand distance of 10.258(1) Å. Pairs of parallel
[Cd(ip)(H2O)2]n motifs are pillared into [Cd2(ip)2(H2O)4(hdn)]n 1D coordination polymer ladders
(Fig. 9b) by anti-anti-anti conformation hdn ligands (torsion angles = 177.6, 180, 177.6°) that
span a Cd···Cd distance of 20.221(8) Å. Neighboring [Cd2(ip)2(H2O)4(hdn)]n ladders stack
along the b crystal direction (Fig. S3) via hydrogen bonding donation from bound water
molecules to ip carboxylate oxygen atoms, and stack along c by means of hydrogen bonding
donation from bound water molecules to the co-crystallized water molecules, and on to hdn
carbonyl groups (Table S1). The co-crystallized water molecules in 4 occupy small incipient
pockets comprising 2.0 % of the unit cell volume.
4.6 Structural description of {[Cd2(tbip)2(H2O)4(hdn)]·H2O}n (5)

The asymmetric unit of compound 5 contains a divalent cadmium atom, a fully
deprotonated tbip ligand, two aqua ligands, a water molecule of crystallization best refined at
half-occupancy, and an hdn ligand with full ligand disorder across a crystallographic inversion
center. The cadmium atom manifests a distorted {CdO6N} pentagonal bipyramidal coordination
environment (Fig. 10a) with bound water molecules in the axial positions. In the equatorial plane
of the pentagonal bipyramid lies a single pyridyl nitrogen donor atom from an hdn ligand, and
chelating carboxylate groups from two tbip ligands. Bond lengths and angles within the
coordination environment are listed in Table 6.
[Cd(H2O)2]2+ coordination fragments are connected into neutral [Cd(tbip)(H2O)2]n
coordination polymer chains that are oriented along the a crystal direction by bis(chelating) tbip
ligands (Fig. 10b) with the Cd···Cd through-ligand distance of 10.146(1) Å delineating the b
lattice parameter. Pairs of parallel [Cd(tbip)(H2O)2]n chain patterns are linked into
[Cd2(tbip)2(H2O)4(hdn)]n 1D coordination polymer ladders by disordered hdn ligands (Fig. 10c)
that connect cadmium atoms at a Cd···Cd distance of 20.54(2) Å. As in 1, both disordered hdn
ligand conformations show an anti-anti-anti disposition of their central aliphatic chains with
four-C atom torsion angles of 173.1, 178.1, and 172.8°. Individual [Cd2(tbip)2(H2O)4(hdn)]n
ladders aggregate into the supramolecular structure of 5 (Fig. S4) via hydrogen bonding donation
from bound water molecules to hdn carbonyl groups (Table S1). Disordered water molecules of
crystallization are located in small regions between the chain motifs, anchored in place by
hydrogen bonding patterns involving the bound water molecules. These occupy 3.7 % of the
unit cell volume.

4.7 Structural description of {[Cd(mip)(hdn)]·H2O}n (6)
The asymmetric unit of compound 6 contains a divalent cadmium atom, a fully
deprotonated mip ligand, an hdn ligand, and a water molecule of crystallization. A distorted
{CdN2O4} octahedral coordination environment is observed at cadmium (Fig. 11), with trans
pyridyl nitrogen donor atoms from two hdn ligands. A chelating carboxylate group from an mip
ligand, and cis-disposed single carboxylate oxygen atoms from two other mip ligands complete
the coordination sphere. Pertinent bond lengths and angles are listed in Table 7.
All mip ligands in 6 adopt an exotridentate bridging mode, with a chelating carboxylate
group binding to one cadmium atom, with the other carboxylate group bridging two cadmium
atoms in a syn-anti fashion. The bridging carboxylate groups form [Cd2(mip)2] units (Fig. 11b)
with embedded {Cd2(OCO)2} clusters; the Cd···Cd through-space distance across the cluster
pattern is 3.890(5) Å. The full span of the mip ligands connect the cluster units into [Cd2(mip)2]n
coordination polymer chains that are arranged parallel to the b crystal direction. These in turn are
pillared into [Cd(mip)(hdn)]n coordination polymer layers (Fig. 12) by pairs of hdn ligands with
an anti-anti-anti conformation of their hexamethylene central moieties (torsion angles = 165.6,
173.6, 172.2°); the through-ligand Cd···Cd distance is 19.12(2) Å. Isolated water molecules of
crystallization occupy small pockets within the layer motif, anchored to the coordination
polymer framework by hydrogen bonding acceptance from hdn N–H groups, and hydrogen
bonding donation to mip carboxylate oxygen atoms (Table S1). As each {Cd2(OCO)2} cluster
can be defined as a 4-connected node, the topology of the [Cd(mip)(hdn)]n layer motif becomes
that of a decorated (4,4) grid. Adjacent [Cd(mip)(hdn)]n layers stack in AAA pattern along the a

crystal direction (Fig. S5) via hydrogen bonding donation from hdn N–H groups in one layer, to
hdn carbonyl groups in a neighboring layer (Table S1).
4.5 Thermal Properties
Compound 1 underwent dehydration in two stages, with a 7.0% mass loss between 140 and 170
°C and a subsequent 2.4% mass loss between 170 and 320 °C. The total 9.4 % mass loss
corresponds roughly to the 8.1 % calculated value for four molar equivalents of water. Ligand
combustion occurred above 320 °C. Compound 2 underwent dehydration between 25 and 120
°C, with a 2.5 % mass loss corresponding to the calculated value of 2.9 % for elimination of two
molar equivalents of water. A subsequent 8.5 % mass loss between 120 and 300 °C corresponded
roughly to a putative elimination of two molar equivalents of NO2 from loss of the nitro
functional groups from the nip ligands. Ligand combustion occurred above 300 °C. Compound
3 showed a 4.0% mass loss between 25 and 215 °C, indicative of partial decarboxylation. Loss of
one molar equivalent of CO2 would have resulted in a mass loss of 5.2 %. Combustion of the
organic components occurred above 215 °C. Compound 4 underwent elimination of all its bound
and unbound water molecules between 25 and 85 °C with the observed mass loss of 11.0 %
exactly matching the predicted value. Ejection of the organic components occurred above 325
°C. Compound 5 underwent dehydration in two stages between 35 and 230 °C with a total mass
loss of 10.3 % corresponding roughly to the calculated value of 8.3 % for elimination of five
molar equivalents of water. Ligand combustion occurred above 230 °C. Compound 6 underwent
dehydration between 25 and 110 °C, with the observed value of 4.0 % slightly higher than the
predicted value of 2.8 % for one molar equivalent of water. This complex may have absorbed

some atmospheric water vapor on long-term storage. Ejection of the organic ligands occurred
above 290 °C. The TGA traces for 1–6 are shown in Figs. S6–S11, respectively.
4.6 Luminescent Properties
Ground samples of compounds 1–6 were subjected to ultraviolet radiation to investigate
the presence of any luminescent behavior. Excitation spectra were recorded by monitoring
emission at 400 nm; the maximum excitation wavelengths (Table 8) were then used to irradiate
the respective samples. Emissive behavior was observed in all cases, with maximum emission
wavelengths as shown in Table 8. Compounds 2 and 3 only showed very weak emission, while
compound 6 manifested a strong emission of blue light. The emission of moderate intensity
violet light was observed for compounds 1, 4, and 5. Emission profiles for 1–6 are depicted in
Fig. 13. The emissive behavior is ascribed to n– or *– molecular orbital electronic transitions
within the aromatic rings of the dicarboxylate ligands (1–6) and the dipyridylamide ligands (1–2,
4–6) after ultraviolet excitation [28]. MLCT or LMCT transitions are very unlikely due to the
closed shell d10 configuration of the divalent zinc or cadmium atoms.
4.7 Nitrobenzene detection
Compounds 4 and 6 were assayed as potential nitrobenzene detectors in ethanol
suspension (insufficient luminescence of 1, 2, 3, and 5 in ethanol suspension precluded further
study). In both cases, emission quenching was observed as L-sized aliquots of a 1  10–4 M
solution of nitrobenzene in DMSO were sequentially added to the coordination polymer ethanol
suspension (Figs. 14 and 15). Electron transfer from the aromatic molecular orbital excited states
in the coordination polymer to the * molecular orbitals of the electron-withdrawing
nitrobenzene analyte is the likely mechanism for the emission quenching in 4 and 6. As seen in

the plots of intensity percent remaining vs L nitrobenzene solution added (Fig. S12), compound
6 undergoes a greater extent luminescence quenching than compound 4 for the same amount of
analyte. It is thus plausible that the nitrobenzene analyte is more easily absorbed in the
interlamellar regions of the stacked layered coordination polymer 6, than between the stacked
ladder motifs in 4.
5. Conclusions
Substituted and unsubstituted isophthalate ligands and the long spanning flexible
dipyridylamide ligand N,N-(hexane-1,6-diyl)dinicotinamide (hdn) afforded a series of 1D ladder
and 2D layered zinc and cadmium coordination polymers. Synergistic effects on the part of the
divalent metal coordination environments, the nature of the 5-position isophthalate substituent,
and the conformational flexibility of the hdn ligands, act during self-assembly to induce the
observed dimensionality and topology. A 3D body centered cubic topology phase was formed
by in situ hydrolysis of the hdn precursor to afford nicotinate ligands. While all of the six
coordination polymers in this series underwent ultraviolet or visible light emission upon
excitation with ultraviolet light, two showed potential as detectors for small quantities of
nitrobenzene in ethanol suspension. The layered phase 6 exhibited stronger luminescence
quenching behavior in the presence of nitrobenzene than did the ladder polymer phase 4, due to
enhanced analyte absorption within the interlamellar regions.
Supplementary Material
Additional molecular graphics and thermogravimetric analysis plots. Crystallographic data
(excluding structure factors) for 1–6 have been deposited with the Cambridge Crystallographic

Data Centre with Nos. 1514939, 1523516, 1514040, 1523517, 1514041, and 1514042,
respectively. Copies of the data can be obtained free of charge via the Internet at
<https://summary.ccdc.cam.ac.uk/structure-summary-form>.
Acknowledgements
Support for this work was provided by the Honors College of Michigan State University.

References
[1] L. D. Tran, J. I. Feldblyum, A. G. Wong-Foy, A. J. Matzger, Langmuir 31 (2015) 2211.
[2] M. Foo, R. Matsuda, Y. Hijikata, R. Krishna, H. Sato, S. Horike, A. Hori, J. Duan, Y. Sato,
Y. Kubota, M. Takata, S. Kitagawa, J. Am. Chem. Soc. 138 (2016) 3022.
[3] P. F. Gao, L. L. Zheng, L. J. Liang, X. X. Yang, Y. F. Li, C. Z. Huang, J. Mater. Chem. B 1
(2013) 3202.
[4] F. Wang, F. Li, M. Xu, H. Yu, J. Zhang, H. Xia, J. Lang, J. Mater. Chem. A 3 (2015) 5908.
[5] L. Carlucci, G. Ciani, D. M. Proserpio, Coord. Chem. Rev. 246 (2003) 247, and references
therein.
[6] T. Fukushima, S. Horike, H. Kobayashi, M. Tsujimoto, S. Isoda, M. Foo, Y. Kubota, M.
Takata, S. Kitagawa, J. Am. Chem. Soc. 134 (2012) 13341.
[7] J. Tao, X.M. Chen, R.B. Huang, L.S. Zheng, J. Solid State Chem. 170 (2003) 130.
[8] a) M. Eddaoudi, J. Kim, N. Rosi, D. Vodak, J. Wachter, M. O'Keeffe, O.M. Yaghi,
Science 295 (2002) 469; b) X.-N. Cheng, W.-X. Zhang, Y.-Y. Lin, Y.-Z. Zheng, X.-M. Chen,
Adv. Mater. 19 (2007) 1494.
[9] B. Chen, C. Liang, J. Yang, D. S. Contreras, Y. L. Clancy, E. B. Lobkovsky, O. M. Yaghi, S.
Dai, Angew. Chem. Int. Ed. 45 (2006) 1390.
[10] Y. He, H. Zhang, Y. Liu, Q. Zhai, Q. Shen, S. Song, J. Ma, Cryst. Growth Des. 14 (2014)
3174.
[11] D. Chen, X. Ma, W. Shi, P. Cheng, Cryst. Growth Des. 15 (2015) 3999.
[12] H. Wang, F. Cheng, C. Zou, Q. Li, Y. Hua, J. Duan, W. Jin, CrystEngComm 18 (2016)
5639.
[13] D. S. Zhou, F. K. Wang, S. Y. Yang, Z. X. Xie and R. B. Huang, CrystEngComm 11 (2009)
2548.
[14] D. P. Martin, M. A. Braverman, R. L. LaDuca, Cryst. Growth Des. 7 (2007) 2609.
[15] A. L. Pochodylo, R. L. LaDuca, CrystEngComm 13 (2011) 2249.
[16] A. L. Pochodylo, C. Y. Wang, R. L. LaDuca, Inorg. Chim. Acta 370 (2011) 449.
[17] X. L. Wang, P. Liu, J. Luan, H. Y. Lin, C. Xu, Z. Naturforsch. 67b (2012) 877.

[18] X. Wang, J. Luan, H. Lin, Q. Lu, C. Xu, G. Liu, Dalton Trans. 42 (2013) 8375.
[19] X. Wang, J. Luan, H. Lin, G. Liu, M. Le, Polyhedron 71 (2014) 111.
[20] T. S. Gardner, E. Wenis, J. J. Lee, J. Org. Chem. 19 (1954) 753.
[21] SAINT, Software for Data Extraction and Reduction, Version 6.02 Bruker AXS, Inc.:
Madison, WI, 2002
[22] SADABS, Software for Empirical Absorption Correction. Version 2.03 Bruker AXS, Inc.:
Madison, WI, 2002
[23] G. M. Sheldrick, SHELXTL, Program for Crystal Structure Refinement, University of
Göttingen: Göttingen, Germany, 1997.
[24] O.V. Dolomanov, L.J. Bourhis, R.J. Gildea, J.A.K. Howard, H. Puschmann, J. Appl Cryst.
42 (2009) 229.
[25] M. Kurmoo, C. Estournes, Y. Oka, H. Kumagai, K. Inoue, Inorg. Chem. 44 (2005) 217.
[26] A. L. Spek, PLATON, A Multipurpose Crystallographic Tool, Utrecht University: Utrecht,
The Netherlands, 1998.
[27] V. A. Blatov, A. P. Shevchenko, D. M. Proserpio, Cryst. Growth Des. 14 (2014) 3576.
TOPOS software is available for download at: http://www.topos.ssu.samara.ru
[28] M. D. Allendorf, C. A. Bauer, R. K. Bhakta, R. J. T. Houk, Chem. Soc. Rev. 38 (2009) 1330
and references therein.

Table 1. Crystal and Structure Refinement Data for 1–6.
Data
1
2
3
Empirical Formula
Formula Weight
Crystal system
Space group
a (Å)
C34H38N4O16Zn2
889.42
C52H54N10O16Zn2
1237.78
triclinic
P
C36H32N2O12Zn3
880.74
triclinic
P
monoclinic
P21/n
10.0927(12)
10.4387(13)
10.5492(14)
102.288(2)
98.709(2)
118.794(3)
908.9(2)
1
9.073(3)
9.580(3)
16.323(5)
73.288(3)
76.785(4)
80.860(4)
1316.2(7)
1
11.1979(13)
12.7884(15)
13.0353(15)
90
b (Å)
c (Å)
 (°)
 (°)
106.3520(10)
90
 (°)
V (Å3)
1791.2(4)
2
Z
D (g cm–3)
1.625
1.562
1.633
 (mm–1)
1.401
0.998
2.059
Min./max. transmission 0.8630
0.7705
0.9092
hkl ranges
–12 ≤h ≤12,
–12 ≤k ≤12,
–12 ≤l ≤12
–10 ≤h ≤10,
–11 ≤k ≤11,
–19 ≤l ≤19
–13 ≤h ≤13,
–15 ≤k ≤9,
–15 ≤l ≤15,
Total reflections
Unique reflections
R(int)
15525
17539
9695
3344
4828
3295
0.0250
300
0.1224
373
0.0418
244
Parameters
0.0407
0.0389
0.1068
0.1050
1.184/–1.108
0.1379
0.0682
0.1971
0.1606
0.812/–0.528
0.0533
0.0403
0.1057
0.0963
0.725/–0.514
R1 (all data)
R1 (I > 2σ(I))
wR2 (all data)
wR2 (I > 2σ(I))
Max/min residual
(e–/ Å3)
G.O.F.
1.080
1.061
1.075

Table 1. Crystal and Structure Refinement Data for 1–6.
Data
4
5
6
Empirical Formula
Formula Weight
Crystal system
Space group
a (Å)
C34H42Cd2N4O16 C42H56Cd2N4O15 C27H30CdN4O7
987.51
1081.70
triclinic
634.95
triclinic
P
triclinic
P
P
10.2581(9)
10.3346(9)
10.9331(10)
85.2730(10)
75.3130(10)
61.1920(10)
981.34(15)
1
10.0640(10)
10.1461(10)
13.2099(13)
88.0940(10)
68.4760(10)
72.5140(10)
1192.3(2)
1
9.1347(9)
10.2596(10)
14.7794(16)
86.965(2)
86.773(2)
76.955(3)
1346.1(2)
2
b (Å)
c (Å)
 (°)
 (°)
 (°)
V (Å3)
Z
D (g cm–3)
1.671
1.507
1.567
 (mm–1)
1.159
0.960
0.864
Min./max. transmission
0.9121
0.9043
0.9448
hkl ranges
–12 ≤h ≤11,
–12 ≤k ≤12,
–13 ≤l ≤13
–12 ≤h ≤11,
–12 ≤k ≤12,
–15 ≤l ≤15
–11 ≤h ≤10,
–12 ≤k ≤12,
–17 ≤l ≤17
Total reflections
Unique reflections
R(int)
16455
13895
22266
3605
4367
4937
0.0369
258
0.0328
273
0.0288
356
Parameters
0.0321
0.0283
0.0718
0.0692
0.682/–0.809
0.0594
0.0533
0.1458
0.1430
1.552/–0.688
0.0265
0.0239
0.0586
0.0567
0.908/–0.333
R1 (all data)
R1 (I > 2σ(I))
wR2 (all data)
wR2 (I > 2σ(I))
Max/min residual
(e–/ Å3)
G.O.F.
1.102
1.221
1.063

Table 2. Selected Bond Distance (Å) and Angle (°) Data for 1.
Zn1–O1
Zn1–O4#1
Zn1–O6
Zn1–N1
1.9866(19) O4#1–Zn1–N1 116.4(5)
1.9935(19) O6–Zn1–O1 109.24(8)
O6–Zn1–O4#1 109.63(9)
1.984(2)
2.04(2)
O6–Zn1–N1
O1–Zn1–N1
113.7(5)
110.6(4)
O1–Zn1–O4#1 95.71(8)
Symmetry transformation: #1 x + 1, y, z.
Table 3. Selected Bond Distance (Å) and Angle (°) Data for 2.
Zn1–O1
1.908(4)
1.935(4)
2.034(5)
2.075(6)
O1–Zn1–N1
O1–Zn1–N4#2
O3#1–Zn1–N1
120.6(2)
109.9(2)
102.8(2)
Zn1–O3#1
Zn1–N1
Zn1–N4#2
O3#1–Zn1–N4#2 96.5(2)
O1–Zn1–O3#1 120.41(19) N1–Zn1–N4#2
102.8(2)
Symmetry transformations: #1 x, y + 1, z; #2 –x + 1, –y + 1, –z + 1.

Table 4. Selected Bond Distance (Å) and Angle (°) Data for 3.
Zn1–O1
2.064(2) O1#1–Zn1–O6#2 94.01(10)
2.064(2) O1#1–Zn1–O6#3 85.99(10)
Zn1–O1#1
Zn1–O3#2
Zn1–O3#3
Zn1–O6#3
Zn1–O6#2
Zn2–O2#4
Zn2–O4
2.073(3) O1–Zn1–O6#2
86.00(10)
2.073(3) O3#3–Zn1–O3#2 180.0
2.096(2) O3#3–Zn1–O6#2 87.84(9)
2.096(2) O3–Zn1–O6#2
92.16(10)
1.952(3) O3#3–Zn1–O6#3 92.16(10)
1.941(2) O3#2–Zn1–O6#3 87.84(10)
1.957(3) O6#3–Zn1–O6#2 180.0
Zn2–O5
Zn2–N1#5
O1–Zn1–O1#1
2.047(3) O2#4–Zn2–O5
116.36(11)
180.0
O2#4–Zn2–N1#5 99.26(11)
O1#1–Zn1–O3#2 91.10(10) O4–Zn2–O2#4
115.54(11)
116.62(11)
99.09(11)
105.85(11)
O1–Zn1–O3#2
88.90(10) O4–Zn2–O5
O1#1–Zn1–O3#3 88.90(10) O4–Zn2–N1#5
O1–Zn1–O3#3
O1–Zn1–O6#3
91.10(10) O5–Zn2–N1#5
94.00(10)
Symmetry transformations: #1 –x + 1, –y + 2, –z; #2 –x + 3/2, –y + 1/2, –z + 1/2;
#3 –x – 1/2, –y + 3/2, z – 1/2; #4 –x + 1/2, –y + 3/2, z + 1/2; #5 –x + 3/2, –y + 1/2, –z + 3/2.
Table 5. Selected Bond Distance (Å) and Angle (°) Data for 4.
Cd1–O1
2.316(2)
O5–Cd1–O2
98.79(7)
Cd1–O2
2.5678(19) O5–Cd1–O3#1 90.37(7)
Cd1–O3#1
Cd1–O4#1
Cd1–O5
2.323(2)
2.616(2)
2.313(2)
2.303(2)
2.312(2)
53.05(7)
85.26(7)
O5–Cd1–O4#1 77.77(7)
O6–Cd1–O1
O6–Cd1–O2
91.75(7)
79.82(7)
Cd1–O6
Cd1–N1
O6–Cd1–O3#1 91.50(7)
O6–Cd1–O4#1 103.41(7)
O1–Cd1–O2
O1–Cd1–O3#1
O1–Cd1–O4#1
O2–Cd1–O4#1
O3#1–Cd1–O2
O6–Cd1–O5
O6–Cd1–N1
178.13(7)
88.89(8)
138.66(8)
86.57(7)
134.52(7) N1–Cd1–O1
170.89(6) N1–Cd1–O2
136.64(7) N1–Cd1–O3#1 136.06(8)
O3#1–Cd1–O4#1 52.27(7)
N1–Cd1–O4#1 84.99(7)
N1–Cd1–O5 89.77(8)
O5–Cd1–O1
88.39(8)
Symmetry transformation: #1 x – 1, y, z.

Table 6. Selected Bond Distance (Å) and Angle (°) Data for 5.
Cd1–O1
2.376(4)
2.466(4)
2.471(3)
2.410(4)
2.320(4)
2.310(5)
2.338(5)
O6–Cd1–O2
O6–Cd1–O3#1
O6–Cd1–O4#1
O6–Cd1–N4#2
N1–Cd1–O1
N1–Cd1–O2
N1–Cd1–O3#1
78.59(14)
98.60(14)
152.00(14)
85.25(15)
105.28(17)
86.05(18)
91.39(16)
95.35(16)
86.71(17)
166.96(18)
87.76(15)
102.36(17)
Cd1–O2
Cd1–O3#1
Cd1–O4#1
Cd1–O6
Cd1–N1
Cd1–N4#2
O1–Cd1–O2
O1–Cd1–O3#1
O1–Cd1–O4#1
O2–Cd1–O3#1
O4#1–Cd1–O2
52.86(13) N1–Cd1–O4#1
130.60(12) N1–Cd1–O6
78.48(13) N1–Cd1–N4#2
176.29(13) N4#2–Cd1–O1
129.40(13) N4#2–Cd1–O2
O4#1–Cd1–O3#1 53.49(12) N4#2–Cd1–O3#1 79.70(15)
O6–Cd1–O1
127.94(14) N4#2–Cd1–O4#1 87.03(15)
Symmetry transformations: #1 x + 1, y, z; #2 x + 1, y + 1, z – 1.
Table 7. Selected Bond Distance (Å) and Angle (°) Data for 6.
O2# –Cd1–O3#
O2# –Cd1–O4#
O2# –Cd1–N1
O2# –Cd1–N4#
O4# –Cd1–O3#
N1–Cd1–O3#
N1–Cd1–O4#
N1–Cd1–N4#
N4# –Cd1–O3#
N4# –Cd1–O4#
Cd1–O1
2.2473(15)
2.2858(16)
2.4422(16)
2.3444(15)
2.3096(18)
2.3347(18)
132.53(6)
85.88(5)
140.84(6)
87.40(6)
93.45(6)
87.98(6)
54.67(5)
95.54(6)
89.82(6)
173.91(6)
87.03(6)
96.16(6)
Cd1–O2#
Cd1–O3#
Cd1–O4#
Cd1–N1
Cd1–N4#
O1–Cd1–O2#
O1–Cd1–O3#
O1–Cd1–O4#
O1–Cd1–N1
O1–Cd1–N4#
140.07(6)
88.02(6)
86.65(6)
Symmetry transformations: #1 –x + 1, –y + 1, –z + 2; #2 x, y – 1, z; #3 x – 1, y + 1, z + 1.

Table 8. Excitation and Emission Spectral Data for 1–6.
Compound
Excitation (max) Emission (max)
(nm)
250
225
250
320
360
360
(nm)
417
298
418
399
460
510
1
2
3
4
5
6

Scheme 1. The dicarboxylate ligands used in this study.
Scheme 2. The dipyridylamide ligand used in this study.