Cadmium Cyanide Research Articles

Negative X-ray expansion in cadmium cyanide

Negative X-ray expansion in cadmium cyanide

Spin-ice physics in cadmium cyanide

Spin-ices are frustrated magnets that support a particularly rich variety of emergent physics. Typically, it is the interplay of magnetic dipole interactions, spin anisotropy, and geometric frustration on the pyrochlore lattice that drives spin-ice formation. The relevant physics occurs at temperatures commensurate with the magnetic interaction strength, which for most systems is 1–5 K. Here, we show that non-magnetic cadmium cyanide, Cd(CN)2, exhibits analogous behaviour to magnetic spin-ices, but does so on a temperature scale that is nearly two orders of magnitude greater. The electric dipole moments of cyanide ions in Cd(CN)2 assume the role of magnetic pseudospins, with the difference in energy scale reflecting the increased strength of electric vs magnetic dipolar interactions. As a result, spin-ice physics influences the structural behaviour of Cd(CN)2 even at room temperature.

Negative X-ray expansion in cadmium cyanide.

Cadmium cyanide, Cd(CN)2, is a flexible coordination polymer best studied for its strong and isotropic negative thermal expansion (NTE) effect. Here we show that this NTE is actually X-ray-exposure dependent: Cd(CN)2 contracts not only on heating but also on irradiation by X-rays. This behaviour contrasts that observed in other beam-sensitive materials, for which X-ray exposure drives lattice expansion. We call this effect ‘negative X-ray expansion’ (NXE) and suggest its origin involves an interaction between X-rays and cyanide ‘flips’; in particular, we rule out local heating as a possible mechanism. Irradiation also affects the nature of a low-temperature phase transition. Our analysis resolves discrepancies in NTE coefficients reported previously on the basis of X-ray diffraction measurements, and we establish the ‘true’ NTE behaviour of Cd(CN)2 across the temperature range 150–750 K. The interplay between irradiation and mechanical response in Cd(CN)2 highlights the potential for exploiting X-ray exposure in the design of functional materials.

Effect of essential oil of black cumin <i>(Nigella sativa)</i> on hematological profiles and total cholesterol levels of Wistar rats exposed by cigarette smoke

Cigarette smoke contains toxic substances such as carbon monoxide, lead, cadmium, tar and hydrogen cyanide which can triggeroxidative stress and causeerythrocyte membrane damage and hemoglobin oxidation. In addition, it also contains nicotine which can increase the total cholesterol levels. Black cumin containing thymoquinone has been known for its antioxidant and anticholesterol activities. This study aimed to investigate the effect of black cumin extract on hematological profiles and total cholesterol levels of Wistar rats exposed by cigarette smoke. It was an experimental study with randomized posttest only control group design. Twenty Wistar rats (Rattus norvegicus) that divided into four groups were used in this study.The normal control group (N) was provided with standard feed,the negative control group (C) was exposed to the cigarette smoke with two pieces of cigarettes/day for 14 days, the treated groups were given black cumin extract 200mg/kg (T1) and 400mg/kg (T2) and exposed by cigarette smoke two pieces of cigarettes/day for 14 days. On day 15, blood samples from the rats were taken through the sinus orbitalis and then the erythrocyte, the hemoglobin and the total cholesterol levels were examined. Data were analyzed using the one-way ANOVA test and continued by the post-hoc test. The results showed the number of erythrocytes and hemoglobin levels of the T2 group was significantly higher than those of the C group (p<0.05). Although, total cholesterol levels of the T2 group was lower than that of other groups, however it was not significantly different (p>0.05). In conclusion, the administration of black cumin extract at 400mg/kg significantly increases the erythrocytes numbers and the hemoglobin levels in Wistar rats exposed by cigarette smoke.

Ice-like disorder and phase transitions in cadmium cyanide

Ice-like disorder and phase transitions in cadmium cyanide

Synthesis and Crystal Structures of Cadmium(II) Cyanide with Branched-Butoxyethanol

Two novel 3D cadmium(II) cyanide coordination polymers with branched-butoxyethanol compounds (iBucel = iso-butoxyethanol, tBucel = tert-butoxyethanol), [{Cd(CN)2(iBucel)2}{Cd(CN)2(H2O)(iBucel)}2{Cd(CN)2}6∙2(iBucel)]n I and [{Cd(CN)2(H2O)1.06(tBucel)0.94}{Cd(CN)2(tBucel)}2{Cd(CN)2}2∙1.06(tBucel)]n II, were synthesized and characterized by structural determination. Complex I contains two distinct Cd(II) coordination geometries: octahedral and tetrahedral. In contrast, complex II contains three distinct Cd(II) coordination geometries: octahedral, square-pyramidal, and tetrahedral. In the two complexes, branched-butoxyethanol molecules behave as both a ligand and a guest in the Cd(CN)2 cavities. The framework in I contains octahedral and tetrahedral Cd(II) in a 3:6 ratio. In I, the coordination environments of octahedral Cd(II) are cis-O-Cd-O. The framework in II contains octahedral, square-pyramidal, and tetrahedral Cd(II) in a 1:2:2 ratio. In II, the coordination environment of octahedral Cd(II) is disordered trans-O-Cd-O and the axial oxygen ligand is either a water or tBucel molecule. In II, the square-pyramidal Cd(II) geometry is formed by one tBucel ligand and four cyanide ligands. The Cd(CN)2 frameworks of the two complexes exhibit different structures.

Local order in cadmium cyanide

Local order in cadmium cyanide

Three-Dimensional Cadmium(II) Cyanide Coordination Polymers with Ethoxy-, Butoxy- and Hexyloxy-ethanol

The three novel cadmium(II) cyanide coordination polymers with alkoxyethanols, [Cd(CN)2(C2H5OCH2CH2OH)]n (I), [{Cd(CN)2(C4H9OCH2CH2OH)}3{Cd(CN)2}]n (II) and [{Cd(CN)2(H2O)2}{Cd(CN)2}3·2(C6H13OCH2CH2OH)]n (III), were synthesized and charcterized by structural determination. Three complexes have three-dimensional Cd(CN)2 frameworks; I has distorted tridymite-like structure, and, II and III have zeolite-like structures. The cavities of Cd(CN)2 frameworks of the complexes are occupied by the alkoxyethanol molecules. In I and II, hydroxyl oxygen atoms of alkoxyethanol molecules coordinate to the Cd(II) ions, and the Cd(II) ions exhibit slightly distort trigonal-bipyramidal coordination geometry. In II, there is also tetrahedral Cd(II) ion which is coordinated by only the four cyanides. The hydroxyl oxygen atoms of alkoxyethanol connects etheric oxygen atoms of the neighboring alkoxyethanol by hydrogen bond in I and II. In III, hexyloxyethanol molecules do not coordinate to the Cd(II) ions, and two water molecules coordnate to the octahedral Cd(II) ions. The framework in III contains octahedral Cd(II) and tetrahedral Cd(II) in a 1:3 ratio. The Cd(CN)2 framework structures depended on the difference of alkyl chain for alkoxyethanol molecules.

Effective treatment of cadmium–cyanide complex by a reagent with combined function of oxidation and coagulation

The treatment of heavy metal–cyanide complex in industrial wastewater generally involves various processing units, such as chemical oxidation, hydrolysis precipitation and coagulation. A novel dual function reagent (PACC), which contains high content of active chlorine and Al13 polymer, shows a promising potential to shorten the process and heighten the treatment efficiency for cadmium–cyanide complex ([Cd(CN)4]2−). The results indicated that PACC is able to simultaneously achieve the complete oxidation of cyanide (CN−) by active chlorine and the subsequent coagulation of cadmium ion (Cd2+) by Al13 polymer. Two stages were carried out for complete CN− oxidation and effective Cd2+ coagulation. The first stage involves the conversion of CN− to cyanate (CNO−), and the second stage involves the conversion of CNO− to nitrogen and the coagulation of the liberated Cd2+. The optimum pH values for the first stage and the second stage are pH 11 and pH 8.5, respectively. The two stages for effective treatment of [Cd(CN)4]2− at the optimal pH condition totally need about 43 min at active chlorine dosage 130% of the theoretical requirement for CN− decomposition. Under the optimal conditions for [Cd(CN)4]2− treatment, the stoichiometric weight ratio of Cl2/Al in PACC is 2. This study presents a novel reagent and method to remove heavy metal–cyanide complexes from wastewater.

Aqua cadmium cyanide coordination polymer with nitronyl nitroxide radical

A new three-dimensional diamagnetic metal nitronyl nitroxide radical coordination polymer with an aqua cadmium cyanide framework Cd(NIT4py)(H 2O)Cd(CN) 4·H 2O 1, was synthesized. X-ray crystallography reveals that the structure consists of 3D aqua cadmium cyanide built up by octahedral Cd II coordinating to NIT4py and tetrahedral Cd II (CN) 4 units. Magnetic measurements show that the χ m T values are nearly constant at higher temperature. The lower χ m T values at lower temperature are related to intermolecular antiferromagnetic interactions of the radicals, which arise due to the hydrogen bonded network ( T N = 21 K).

A high-pressure micro-Raman spectroscopic study of copper cyanide, CuCN

There has been growing interest in materials that exhibit negative thermal expansion properties [1]. The largest magnitudes described so far involve metal cyanide complexes such as Prussian Blue analogues in which metal atoms at the corners of cubes are linked by cyanide groups along the edges [2–4], and the interpenetrating tetrahedral (diamond-like) lattices of zinc, and cadmium cyanides [5–10]. Although the same atomic sequence M–C–N–M occurs in the cyanides of copper, silver, and gold, these compounds do not form a three-dimensional lattice but consist of infinite chains in the solid state [11–14]. Furthermore, the structure of copper cyanide is polymorphic with a low-temperature (LT-CuCN) form that transforms irreversibly to a second form (high-temperature; HT-CuCN) upon heating above 550 K. In LT-CuCN, the infinite chains are not linear and show a wave-like structure, whereas HT-CuCN is linear. The chain structures are disordered with respect to the carbon and nitrogen atom positions [15]. The negative thermal expansion arises from thermally activated transverse vibrations of the M–C–N–M groups, which increase in amplitude with increasing temperature leading to a decrease in the M...M distance. In chain systems, the transverse cyanide vibrational modes would shorten the unit cell in one direction and lengthen it in another, causing an anisotropic thermal expansion. In the case of HT-CuCN, the X-ray diffraction measurements of the trigonal unit cell dimensions as a function of temperature showed that a normal positive increase occurs along the a-axis and there is a small decrease along the c-axis of the unit cell [12]. A property of particular interest for negative thermal expansion materials is the mode Gruneisen parameter, ci, which represents the volume dependence of the mode frequency and can be written as B0d(ln(mi))/dP, where B0 is the bulk modulus. A negative value of a mode Gruneisen parameter is shown by a negative value of the pressure dependence of the vibrational frequency and this provides a method of determining which vibrational modes contribute to the negative thermal expansion.

Cadmium cyanide complexes with heterocyclic thiones: Solid state and solution NMR studies

Cadmium(II)cyanide complexes of various thiones (imidazolidine-2-thione, diazinane-2-thione and their derivatives) have been prepared and characterized by elemental analysis, IR and solid as well as solution NMR spectroscopy. It appears from the IR data that all complexes are non-ionic [(>C S) 2Cd(CN) 2]. An upfield shift in the 13C NMR and downfield shifts in the 1H NMR are consistent with the sulfur coordination to cadmium(II). The solid 113Cd NMR data show the presence of different coordination numbers in some complexes.

Nanoporosity and Exceptional Negative Thermal Expansion in Single‐Network Cadmium Cyanide

Negative Schwingungen: Eine Netzwerkstruktur aus Cadmiumcyanid zeigt eine unerwartet starke isotrope negative thermische Ausdehnung über einen großen Temperaturbereich (siehe Auftragung des Elementarzellparameters a gegen die Temperatur). Gastmoleküle in den Poren der Gerüststruktur blockieren die transversalen Schwingungsmoden, die für dieses Verhalten maßgeblich sind, sodass der Wert des Linearkoeffizienten der thermischen Ausdehnung mit der Besetzung durch Gastmoleküle steigt.

Nanoporosity and Exceptional Negative Thermal Expansion in Single‐Network Cadmium Cyanide

Accentuate the negative: Single-network cadmium cyanide displays isotropic negative thermal expansion behavior of unprecedented magnitude over a large temperature range (see graph of unit cell parameter a versus temperature). Guest molecules in the pores of this framework block the transverse vibrational modes responsible for this behavior, causing the value of the linear coefficient of thermal expansion to increase with guest occupancy.

Impact forging of sintered steel preforms

The treatment of heavy metal–cyanide complex in industrial wastewater generally involves various processing units, such as chemical oxidation, hydrolysis precipitation and coagulation. A novel dual function reagent (PACC), which contains high content of active chlorine and Al13 polymer, shows a promising potential to shorten the process and heighten the treatment efficiency for cadmium–cyanide complex ([Cd(CN)4]2−). The results indicated that PACC is able to simultaneously achieve the complete oxidation of cyanide (CN−) by active chlorine and the subsequent coagulation of cadmium ion (Cd2+) by Al13 polymer. Two stages were carried out for complete CN− oxidation and effective Cd2+ coagulation. The first stage involves the conversion of CN− to cyanate (CNO−), and the second stage involves the conversion of CNO− to nitrogen and the coagulation of the liberated Cd2+. The optimum pH values for the first stage and the second stage are pH 11 and pH 8.5, respectively. The two stages for effective treatment of [Cd(CN)4]2− at the optimal pH condition totally need about 43 min at active chlorine dosage 130% of the theoretical requirement for CN− decomposition. Under the optimal conditions for [Cd(CN)4]2− treatment, the stoichiometric weight ratio of Cl2/Al in PACC is 2. This study presents a novel reagent and method to remove heavy metal–cyanide complexes from wastewater.

A Reexamination of the Structure of “Honeycomb Cadmium Cyanide”

The low-temperature crystal structure of Cd(CN)2·2/3H2O·t-BuOH (230 K) is reported, Pbcm, a=8.694(1), b=16.908(4), c=21.157(3) Å. Although the cell has approximately twice the volume of the previously reported room temperature cell the 3D cadmium-cyanide framework has essentially the same connectivity. The hydrogen bonded t-BuOH/H2O system is much better defined at low temperature and this new insight together with solid-state NMR data afford an improved model of the room temperature structure, which is now reported in the space group Cmmm.

New two- and three-dimensional [Cd(CN) 2] n frameworks formed with cadmium cyanide and 2,2'–bipyridine and 4,4'–bipyridine

The two cadmium cyanide complexes Cd(CN) 2 (4,4'–bipy) 0.5 (1) and [Cd(2,2'–bipy)(CN) 2] 3·H 2O (2) show infinite 3D and 2D [Cd(CN) 2] n framework structures, respectively. The cadmium cyanide framework in 1 is topologically the same as the cristobalite-like [Cd(CN) 2] n framework but is severely distorted. A 4,4'–bipyridine molecule is trapped in each ‘supercage’ which is formed from two adjacent adamantane-like cadmium cyanide cages. In 2, the bidentate 2,2'–bipyridine ligands are coordinated to cadmium centers to prevent expansion of the 2D cadmium cyanide framework into a 3D framework.

A three-dimensional framework formed from cadmium(II) cyanide and 1-methylimidazole

The three-dimensional structure of octacyanotetrakis(1-methylimidazole-N 3 )tetracadmium(II) clathrate, [Cd 4 (CN) 8 (C 4 H 6 N 2 ) 4 ], contains three kinds of Cd atoms, i.e. tetrahedral Cd1 and octahedral Cd2 and Cd3 in a 2:1:1 ratio; atoms Cd2 and Cd3 lie on inversion centres. The Cd1 and Cd2 centres are coordinated by four and six cyano groups, respectively. The Cd3 centre is coordinated by two cyano groups and four 1-methylimidazole ligands. The three-dimensional framework provides hexagonal channels which are occupied by 1-methylimidazole ligands coordinated to the Cd3 centre.

A three-dimensional framework formed from cadmium(II) cyanide and 1-methylimidazole

The three-dimensional structure of octacyanotetrakis(1-methylimidazole-N 3 )tetracadmium(II) clathrate, [Cd 4 (CN) 8 (C 4 H 6 N 2 ) 4 ], contains three kinds of Cd atoms, i.e. tetrahedral Cd1 and octahedral Cd2 and Cd3 in a 2:1:1 ratio; atoms Cd2 and Cd3 lie on inversion centres. The Cd1 and Cd2 centres are coordinated by four and six cyano groups, respectively. The Cd3 centre is coordinated by two cyano groups and four 1-methylimidazole ligands. The three-dimensional framework provides hexagonal channels which are occupied by 1-methylimidazole ligands coordinated to the Cd3 centre.

Mineralomimetic cadmium cyanide benzene clathrate

A new mineralomimetic cadmium cyanide benzene clathrate Cd(CN)2-C6H6 (1) has been obtained. The new mineralomimetic cadmium cyanide host Cd(CN)2 framework belongs to cristobalitelike structures. The new clathrate1 crystallized in the trigonal space group R3m (No. 166), a= 8.953(4), c-21.929(6) a. The structure of1 is slightly different from that of the reported cyclohexane clathrate Cd(CN)2-C6H12 with space group Fd3m, which is similar to H-cristobalite.