Control of Intramolecular Hydrogen Bonding in a Conformation-Switchable Helical-Spring Polymer by Solvent and Temperature

A substituted poly(phenylacetylene) derivative (PPA_HB) with two hydroxymethyl groups at the meta position of the side phenyl ring was examined as a conformation-switchable helical spring polymer that responds to solvent and heat stimuli in a precisely controlled manner. Intramolecular hydrogen bonds, which cause the helical structure of the polymer, were broken and re-formed by adjusting the hydrogen-bonding strength values (pK_HB) of various combinations of solvents or by varying the temperature. In this process, a reversible conformational change from cis–cisoid to cis–transoid, accompanied by a phase transition in the form of a helix-coil transformation occurred, with the polymer exhibiting critical changes of color fading and recovery in specific environments. These results demonstrate that PPA_HB can be used as either a pK_HB indicator or a thermometer. The color changes of the polymer solution are described in detail based on spectroscopic analyses and thermodynamic considerations.     

Origin of the color of π‐conjugated columnar polymers: Poly(p‐n‐octylthiophenyl)acetylene prepared using a [Rh(norbornadiene)Cl]2 catalyst

Highly stereospecific polymerization of a novel sulfur containing aromatic acetylenes, that is, (p‐n‐octylthiophenyl)acetylene (pOctSPA), was successfully performed using the Rh complex, [Rh(norbornadiene)Cl]₂‐TEA, catalyst in the presence of various solvents under mild conditions. The resulting polymers were characterized in detail by ¹H NMR, ESR, laser Raman, diffuse reflective UV‐Vis (DRUV‐Vis), and wide angle X‐ray diffraction methods. The data showed that the resulting polymers bear cis‐transoid form, which can induce the cis‐to‐trans isomerization when the cis polymers are subjected to pressure at room temperature under vacuum, breaking rotationally the cis C?C bonds in the main‐chain giving two kinds of π‐radicals, the so‐called cis radical and trans radical as the origin of a polymer magnet like a novel spin glass material. Further, the resulting cis poly(acetylene)s were found to have a helical main‐chain, which is packed in pseudohexagonal crystal called π‐conjugated columnar or nano π‐conjugated columnar as a novel color controllable material. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 2836–2850, 2005     

Synthesis and photoisomerization of poly(1‐methylpropargyl ester)s carrying azobenzene moieties

Optically active 1‐methylpropargyl esters bearing azobenzene groups, namely, (S)‐(?)‐3‐methyl‐3‐{4‐[4‐(n‐butyloxy)phenylazophenyl]carbonyl}oxy‐1‐propyne ( 1 ), (S)‐(?)‐3‐methyl‐3‐{4‐[4‐(n‐hexyloxy)phenylazophenyl]carbonyl}oxy‐1‐propyne ( 2 ), and (S)‐(?)‐3‐methyl‐3‐{4‐[4‐(n‐octyloxy)phenylazophenyl]carbonyl}oxy‐1‐propyne ( 3 ) were synthesized and polymerized with Rh⁺(nbd)[η⁶‐C₆H₅B^?(C₆H₅)₃] (nbd, norbornadiene) as a catalyst to afford the corresponding poly(1‐methyloropargyl ester)s with moderate molecular weights (M_n = 24,000–31,300) in good yields (79–84%). Polymers were soluble in common organic solvents including toluene, CHCl₃, CH₂Cl₂, THF, and DMSO, whereas insoluble in diethyl ether, n‐hexane, and methanol. Large optical rotations and strong CD signals demonstrated that all the polymers take a helical structure with a predominantly one‐handed screw sense. The helical structure of the polymers changed with the addition of MeOH and heat. The trans‐azobenzene of the polymer side chains isomerized into cis on UV irradiation, which was accompanied with drastic helical conformational changes of the polymer backbone. The cis‐azobenzene moiety reisomerized into trans on visible‐light irradiation, which induced the recovery of chiral geometry of azobenzene moieties in the side chain. Conformational analysis revealed that the polymers form a tightly twisted right‐handed helical structure with a dihedral angle of 70° at the single bond of the main chain. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 4749–4761, 2009     

Cationic photopolymerization of cis‐2,3‐tetramethylene‐1,4,6‐trioxaspiro[4,4]nonane

The spiro‐orthoester, cis‐2,3‐tetramethylene‐1,4,6‐trioxaspiro[4,4]nonane (cis‐TTN) ( I ), underwent rapid cationic photopolymerization when exposed to UV light using diphenyliodonium salts as a photoinitiator. The polymer, poly[(trans‐OCB)_x′‐(cis‐OCB)_x″‐(CHO)_y] thus formed consisted of poly(trans‐2‐oxycyclohexyl butanoate) (trans‐OCB)_x′ ( II ), poly(cis‐2‐oxycyclohexyl butanoate) (cis‐OCB)_x″ ( III ), and poly‐ (1,2‐cyclohexene oxide) (CHO)_y segments, and no expected pure poly(ether‐ester), that is, poly(2‐oxycyclohexyl butanoate), was isolated. The structure of the polymer was identified, and the mechanism of the reaction was deduced. The polymer thus formed exhibited expansion in volume during cationic photopolymerization when compared to that obtained by conventional cationic polymerization using a Lewis acid (e.g., BF₃OEt₂, CH₃OSO₂CF₃, or SnCl₄) as an initiator, which demonstrated volume shrinkage during polymerization. The volume expansion of the polymer during polymerization was due to (1) the lower content of the higher density (CHO)_y segment in the polymer chain and, more importantly, (2) the higher and optimal mole ratio of (trans‐OCB)_x′ and (cis‐OCB)_x″ segments that led the polymer in a more disordered, less dense, and higher volumetric state. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 3680–3690, 2009     

Poly(L‐lysine)‐Induced Aggregation of Single‐Strand Oligo‐DNA‐Modified Gold Nanoparticles

Single‐strand oligo‐DNA‐modified Au nanoparticles (AuNPs) undergo aggregation in the presence of poly(L ‐lysine) (PLL), which is attributed to the interactions between the oligo‐DNA and PLL. These interactions between the oligo‐DNA and PLL were identified to be electrostatic when the lysine residues of PLL were positively charged and to be hydrogen bonding when the residues were deprotonated. The aggregation was promoted with an increase in the pH value at a pH level lower than the pK_a value of PLL (pK_a≈10.0) due to the gradual deprotonation of the lysine residues and thus suppressed electrostatic interactions between the positively charged lysine residues of PLL and the negatively charged backbone phosphate groups of the oligo‐DNA. At pH levels higher than the pK_a value of PLL, the aggregation was identified to be dominated by the hydrogen bonds between the bases of the oligo‐DNA and the deprotonated lysine residues of PLL. This study prompts the possibility that the spectral, and thus color, change of AuNPs upon aggregation can be used as a probe to follow the interactions between oligo‐DNA and polypeptides.     

A Reversible Proton Relay Process Mediated by Hydrogen‐Bonding Interactions in [FeFe]Hydrogenase Modeling

A reversible and temperature‐dependent proton‐relay process is demonstrated for a Fe₂ complex possessing a terminal thiolate in the presence of nitrogen‐based acids. The terminal sulfur site (S^t) of the complex forms a hydrogen‐bond interaction with N,N‐dimethylanilinium acid at 183 K. The Fe₂ core, instead, is protonated to generate a bridging hydride at 298 K. Reversibility is observed for the tautomerization between the hydrogen‐bonded pair and the Fe–hydride species. X‐ray structural analysis of the hydrogen‐bonded species at 193 K reveals a short N(H)???S^t contact. Employment of pyridinium acid also results in similar behavior, with reversible proton–hydride interconversion. DFT investigation of the proton‐transfer pathways indicates that the pK_a value of the hydrogen‐bonded species is enhanced by 3.2 pK_a units when the temperature is decreased from 298 K to 183 K.     

Structure–Reactivity Relationship in the Frustrated Lewis Pair (FLP)‐Catalyzed Hydrogenation of Imines

The autoinduced, frustrated Lewis pair (FLP)‐catalyzed hydrogenation of 16‐benzene‐ring substituted N‐benzylidene‐tert‐butylamines with B(2,6‐F₂C₆H₃)₃ and molecular hydrogen was investigated by kinetic analysis. The pK_a values for imines and for the corresponding amines were determined by quantum‐mechanical methods and provided a direct proportional relationship. The correlation of the two rate constants k₁ (simple catalytic cycle) and k₂ (autoinduced catalytic cycle) with pK_a difference between imine and amine pairs (ΔpK_a) or Hammett's σ parameter served as useful parameters to establish a structure–reactivity relationship for the FLP‐catalyzed hydrogenation of imines.     

Helical polyacetylenes carrying 2,2,6,6‐tetramethyl‐1‐piperidinyloxy and 2,2,5,5‐tetramethyl‐1‐pyrrolidinyloxy moieties: Their synthesis,properties, and function

2,2,6,6‐Tetramethyl‐1‐piperidinyloxy (TEMPO)‐ and 2,2,5,5‐tetramethyl‐1‐pyrrolidinyloxy (PROXYL)‐containing (R)‐1‐methylpropargyl TEMPO‐4‐carboxylate ( 1 ), (R)‐1‐methylpropargyl PROXYL‐3‐carboxylate ( 2 ), (rac)‐1‐methylpropargyl PROXYL‐3‐carboxylate ( 3 ), (S)‐1‐propargylcarbamoylethyl TEMPO‐4‐carboxylate ( 4 ), and (S)‐1‐propargyloxycarbonylethyl TEMPO‐4‐carboxylate ( 5 ) (TEMPO, PROXYL) were polymerized to afford novel polymers containing the TEMPO and PROXYL radicals at high densities. Monomers 1–3 and 5 provided polymers with moderate number‐average molecular weights of 8200–140,900 in 49–97% yields in the presence of (nbd)Rh⁺[η⁶‐C₆H₅B^?(C₆H₅)₃], whereas 4 gave no polymer with this catalyst but gave polymers possessing low M_n (3800–7500) in 56–61% yield with [(nbd)RhCl]₂‐Et₃N. Poly( 1 ), poly( 2 ), and poly( 4 ) took a helical structure with predominantly one‐handed screw sense in THF and CHCl₃ as well as in film state. The helical structure of poly( 1 ) and poly( 2 ) was stable upon heating and addition of MeOH, whereas poly( 4 ) was responsive to heat and solvents. All of the free radical‐containing polymers displayed the reversible charge/discharge processes, whose capacities were in a range of 43.2–112 A h/kg. In particular, the capacities of poly( 2 )–poly( 5 )‐based cells reached about 90–100% of the theoretical values regardless of the secondary structure of the polymer, helix and random. Poly( 1 ), poly( 2 ), and poly( 4 ) taking a helical structure exhibited better capacity tolerance towards the increase of current density than nonhelical poly( 3 ) and poly( 5 ) did. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 5431–5445, 2007     

[2‐(2‐Pyridyl)‐1H‐benzimidazole‐κ2N2,N3]bis(p‐toluato‐κ2O,O′)manganese(II)

In the title compound, [Mn(C₈H₇O₂)₂(C₁₂H₉N₃)], the manganese(II) centre is surrounded by three bidentate chelating ligands, namely, one 2‐(2‐pyridyl)benzimidazole ligand [Mn—N = 2.1954 (13) and 2.2595 (14) Å] and two p‐toluate ligands [Mn—O = 2.1559 (13)–2.2748 (14) Å]. It displays a severely distorted octahedral geometry, with cis angles ranging from 58.87 (4) to 106.49 (5)°. Intermolecular C—H...O hydrogen bonds between the p‐toluate ligands link the molecules into infinite chains, and every two neighbouring chains are further coupled by N—H...O and C—H...O hydrogen bonds between the 2‐(2‐pyridyl)benzimidazole and p‐toluate ligands, leading to an infinite ribbon‐like double‐chain packing mode. The complete solid‐state structure can be described as a three‐dimensional supramolecular framework, stabilized by these intermolecular hydrogen‐bonding interactions and possible C—H...π interactions, as well as stacking interactions involving the 2‐(2‐pyridyl)benzimidazole ligands.     

Anion Recognition with Hydrogen‐Bonding Cyclodiphosphazanes

Modular cyclodiphosph(V)azanes are synthesised and their affinity for chloride and actetate anions were compared to those of a bisaryl urea derivative ( 1 ). The diamidocyclodiphosph(V)azanes cis‐[{ArNHP(O)(μ‐tBu)}₂] [Ar=Ph ( 2 ) and Ar=m‐(CF₃)₂Ph ( 3 )] were synthesised by reaction of [{ClP(μ‐NtBu)}₂] ( 4 ) with the respective anilines and subsequent oxidation with H₂O₂. Phosphazanes 2 and 3 were obtained as the cis isomers and were characterised by multinuclear NMR spectroscopy, FTIR spectroscopy, HRMS and single‐crystal X‐ray diffraction. The cyclodiphosphazanes 2 and 3 readily co‐crystallise with donor solvents such as MeOH, EtOH and DMSO through bidentate hydrogen bonding, as shown in the X‐ray analyses. Cyclodiphosphazane 3 showed a remarkably high affinity (log[K]=5.42) for chloride compared with the bisaryl urea derivative 1 (log[K]=4.25). The affinities for acetate (AcO^?) are in the same range ( 3 : log[K]=6.72, 1 : log[K]=6.91). Cyclodiphosphazane 2 , which does not contain CF₃ groups, exhibits weaker binding to chloride (log[K]=3.95) and acetate (log[K]=4.49). DFT computations and X‐ray analyses indicate that a squaramide‐like hydrogen‐bond directionality and C_α?H interactions account for the efficiency of 3 as an anion receptor. The C_α?H groups stabilise the Z,Z‐ 3 conformation, which is necessary for bidentate hydrogen bonding, as well as coordinating with the anion.     

Cadmium(II) Complexes with Mixed cis‐Epoxysuccinate and 2,2′‐Bipyridyl‐Like Ligands: Syntheses,Crystal Structures,and Luminescent Properties

Two new Cd^II complexes, [Cd( ces )(phen)]_∞ ( 1 ) and {[Cd( ces )(bpy)(H₂O)](H₂O)}₂ ( 2 ), were prepared by slow solvent evaporation methods from mixtures of cis‐epoxysuccinic acid and Cd(ClO₄)₂ · 6H₂O in the presence of phen or bpy co‐ligand ( ces = cis‐epoxysuccinate, phen = 1,10‐phenanthroline, and bpy = 2,2′‐bipyridine). Single‐crystal X‐ray diffraction analyses show that complex 1 has a one‐dimensional (1D) helical chain that is further assembled into a two‐dimensional (2D) sheet, and then an overall three‐dimensional (3D) network by the interchain C–H ··· O hydrogen bonds. Complex 2 features a dinuclear structure, which is further interlinked into a 3D supramolecular network by the co‐effects of intermolecular C–H ··· O and C–H ··· π hydrogen bonds as well as π ··· π stacking interactions. The structural differences between 1 and 2 are attributable to the intervention of different 2,2′‐bipyridyl‐like co‐ligands. Moreover, 1 and 2 exhibit intense solid‐state luminescence at room temperature, which mainly originates from the intraligand π→π* transitions of aromatic co‐ligands.     

Stereocomplementary Synthesis of cis‐ and trans‐2‐(p‐Bromophenyl)‐5‐methylthiazolidin‐4‐ones: Useful Umpolung‐type Suzuki–Miyaura Cross‐coupling Partner and Donor

Novel cis‐ and trans‐2‐(p‐bromophenyl)‐5‐methylthiazolidin‐4‐ones, S,N‐containing heterocyclic compounds, were provided in a cis‐stereocomplementary and trans‐stereocomplementary synthetic manner. cis‐Selective cyclo‐condensation proceeded between 2‐sulfanylpropanoic acid (thiolactic acid) and an imine derived from 4‐bromobenzaldehyde and methylamine, whereas Ti(OiPr)₄ and Ti(OiBu)₄‐promoted trans‐selective cyclo‐condensation proceeded between benzyl 2‐sulfanylpropanoate and the imine. The obtained cis‐ and trans ‐ 2‐(p‐bromophenyl)‐5‐methylthiazolidin‐4‐ones were successfully converted to 2‐(3‐furyl)phenyl derivatives and bis(pinacolato)diborane derivatives utilizing Suzuki–Miyaura and Miyaura–Ishiyama cross‐coupling reactions, respectively, in an umpolung manner.     

New Types of Planar Chiral [2.2]Paracyclophanes and Construction of One‐Handed Double Helices

New types of planar chiral (R_p)‐ and (S_p)‐4,7,12,15‐tetrasubstituted [2.2]paracyclophanes were synthesized from racemic 4,12‐dihydroxy[2.2]paracyclophane as the starting compound. Regioselective dibromination and transformation afforded a series of planar chiral (R_p)‐ and (S_p)‐4,7,12,15‐tetrasubstituted [2.2]paracyclophanes, which can be used as chiral building blocks. In this study, left‐ and right‐handed double helical structures were constructed via chemoselective Sonogashira–Hagihara coupling. The double helical compounds were excellent circularly polarized luminescence (CPL) emitters with large molar extinction coefficients, good photoluminescence quantum efficiencies, and large CPL dissymmetry factors.     

Hydrogen bonding in polyamino‐polyalcohols: a monohydrated cocrystal of 1,3‐diamino‐5‐azaniumyl‐1,3,5‐trideoxy‐cis‐inositol iodide and 1,3,5‐triamino‐1,3,5‐trideoxy‐cis‐inositol

In the title monohydrated cocrystal, namely 1,3‐diamino‐5‐azaniumyl‐1,3,5‐trideoxy‐cis‐inositol iodide–1,3,5‐triamino‐1,3,5‐trideoxy‐cis‐inositol–water (1/1/1), C₆H₁₆N₃O₃⁺·I⁻·C₆H₁₅N₃O₃·H₂O, the neutral 1,3,5‐triamino‐1,3,5‐trideoxy‐cis‐inositol (taci) molecule and the monoprotonated 1,3‐diamino‐5‐azaniumyl‐1,3,5‐trideoxy‐cis‐inositol cation (Htaci⁺) both adopt a chair conformation, with the three O atoms in axial and the three N atoms in equatorial positions. The cation, but not the neutral taci unit, exhibits intramolecular O—H...O hydrogen bonding. The entire structure is stabilized by a complex three‐dimensional network of intermolecular hydrogen bonds. The neutral taci entities and the Htaci⁺ cations are each aligned into chains along [001]. In these chains, two O—H...N interactions generate a ten‐membered ring as the predominant structural motif. The rings consist of vicinal 2‐amino‐1‐hydroxyethylene units of neighbouring molecules, which are paired via centres of inversion. The chains are interconnected into undulating layers parallel to the ac plane, and the layers are further held together by O—H...N hydrogen bonds and additional interactions with the iodide counter‐anions and solvent water molecules.     

Solvo‐thermal Preparation of One Novel Cadmium(II) Coordination Polymer with 1‐(4‐Aminobenzyl)‐1,2,4‐Triazole and Bi‐functional Photo‐Luminescent Sensing for Acetone and Dichromate

In this work a 1,2,4‐triazole derivative 1‐(4‐aminobenzyl)‐1,2,4‐triazole (abtz) was utilized, one new cadmium(II) coordination polymer, namely [Cd(abtz)I₂]_n ( 1 ) was prepared through the powerful solvo‐thermal synthetic strategy. In compound 1 , the abtz building blocks are interlinked through the central Cd^II ions forming the two‐dimensional (2D) layer coordination framework. Powder X‐ray diffraction (PXRD) characterization also reveals that we have prepared the pure phases of coordination polymer 1 . Optical properties have been determined, which can behave the excellent photo‐luminescent emission of coordination polymer 1 . Photo‐luminescent experiment also reveals that coordination polymer 1 can behave the highly sensitive detection for acetone molecules with high K_sv value (K_sv = 4.12 ×10⁴ L · mol^–1) in the recyclable detection fashion. Additionally, coordination polymer 1 also can behave the highly sensitive detection for pollutant dichromate with excellent quenching efficiency K_sv (K_sv = 2.12 × 10⁴ L · mol^–1) and low detection limit [38 × 10^–3 mM (S/N = 3)]. UV/Vis, photo‐luminescent lifetime, and PXRD patterns also have been determined to analyze the detection mechanism.     

catena‐Poly[thorium(IV)‐tetrakis(μ2‐3‐carboxyadamantane‐1‐carboxylato)]: a quadruple helical strand driven by a synergy of coordination and hydrogen bonding

The title compound, [Th(C₁₂H₁₅O₄)₄]_n, is the first homoleptic thorium–carboxylate coordination polymer. It has a one‐dimensional structure supported by the bidentate bridging coordination of the singly charged 3‐carboxyadamantane‐1‐carboxylate (HADC⁻) anions. The metal ion is situated on a fourfold axis (site symmetry 4) and possesses a square‐antiprismatic ThO₈ coordination, including four bonds to anionic carboxylate groups [Th—O = 2.359 (2) Å] and four to neutral carboxyl groups [Th—O = 2.426 (2) Å], while a strong hydrogen bond between these two kinds of O‐atom donor [O...O = 2.494 (3) Å] affords planar pseudo‐chelated Th{CO₂...HO₂C} cycles. This combination of coordination and hydrogen bonding is responsible for the generation of quadruple helical strands of HADC⁻ ligands, which are wrapped around a linear chain of Th^IV ions [Th...Th = 7.5240 (4) Å] defining the helical axis.     

A one‐dimensional carboxyl­ate‐bridged helical copper(II) complex containing (quinolin‐8‐yl­oxy)­acetate

The title compound, catena‐poly[­[bromo­copper(II)]‐μ‐(quin­olin‐8‐yl­oxy)­acetato‐κ⁴N,O,O′:O′′], [CuBr(C₁₁H₈NO₃)]_n, is a novel carboxyl­ate‐bridged one‐dimensional helical copper(II) polymer. The metal ion exhibits an approximately square‐pyramidal CuBrNO₃ coordination environment, with the three donor atoms of the ligand and the bromide ion occupying the basal positions, and an O atom belonging to the carboxyl­ate group of an adjacent mol­ecule in the apical site. Carboxyl­ate groups are mutually cis oriented, and each anti–anti carboxyl­ate group bridges two copper(II) ions via one apical and one basal position [Cu⋯Cu = 5.677 (1) Å], resulting in the formation of a helical chain along the crystallographic b axis.     

Crystal Structure and Spectroscopic Properties of cis‐β‐Diazido(1,4,7,11‐tetraazaundecane)chromium(III) Bromide

The new complex, cis‐β‐[Cr(2,2,3‐tet)(N₃)₂]Br (2,2,3‐tet = 1,4,7,11‐tetraazaundecane), was prepared and its structure was determined by single‐crystal X‐ray diffraction. The chromium(III) atom is in a distorted octahedral environment coordinated by four nitrogen atoms of 2,2,3‐tet and two azido ligands in a cis‐β arrangement, with bent Cr–N₃ linkages at the coordinating azide nitrogen atoms. The mean Cr–N(2,2,3‐tet) and Cr–N(azide) bond lengths are 2.084(5) and 2.021(5) Å, respectively. The crystal structure is stabilized by ionic interactions, supported by N–H ··· N(azide) and N–H ··· Br hydrogen bonds. The IR and electronic spectroscopic properties are also discussed.     

Protonation‐Dependent Base Flipping at Neutral pH in the Catalytic Triad of a Self‐Splicing Bacterial Group II Intron

NMR spectroscopy has revealed pH‐dependent structural changes in the highly conserved catalytic domain 5 of a bacterial group II intron. Two adenines with pK_a values close to neutral pH were identified in the catalytic triad and the bulge. Protonation of the adenine opposite to the catalytic triad is stabilized within a G(syn)–AH⁺(anti) base pair. The pH‐dependent anti‐to‐syn flipping of this G in the catalytic triad modulates the known interaction with the linker region between domains 2 and 3 (J23) and simultaneously the binding of the catalytic Mg²⁺ ion to its backbone. Hence, this here identified shifted pK_a value controls the conformational change between the two steps of splicing.     

{Δ‐1,4,7,10‐Tetrakis[(S)‐2‐hydroxy­propyl‐κO]‐1,4,7,10‐tetra­aza­cyclo­do­dec­ane‐κ4N}cad­mium(II) 4‐nitrophenolate per­chlor­ate hydrate

Crystallization of [Cd(S‐thpc12)](ClO₄)₂·H₂O {S‐thpc12 is 1,4,7,10‐tetra­kis[(S)‐2‐hy­drox­y­propyl]‐1,4,7,10‐tetra­aza­cy­clo‐do­dec­ane} in the presence of sodium p‐nitrophenolate forms the title complex, [Cd(C₂₀H₄₄N₄O₄)](C₆H₄NO₃)(ClO₄)·H₂O, in which p‐nitrophenolate and water separately hydrogen bond to a different pair of cis‐related pendant hydroxyl groups which, together with the four N atoms, are themselves bound to Cd^II in an approximately square antiprismatic arrangement. The diastereoselectivity of the complex‐forming process is apparent from the fact that both different disymmetric cations in the asymmetric unit have the same Δ helicity.