SPEC Process II. Adsorption of strontium and some typical co-existent elements contained in high level liquid waste onto a macroporous silica-based crown ether impregnated functional composite

To separate Sr(II), one of the heat emitting nuclides, from high level liquid waste (HLLW), a macroporous silica-based DtBuCH18C6 polymeric composite, DtOct/SiO₂-P, was synthesized by means of molecular modification of 4,4′,(5′)-di(tert-butylcyclohexano)-18-crown-6 (DtBuC H18C6) with a long-chain 1-octanol. It was performed by impregnating and immobilizing DtBuCH18C6 and 1-octanol molecules into the pores of the SiO₂-P particles, the macroporous silica-based support. The adsorption of Sr(II) and some co-existent typical elements Na(I), K(I), Cs(I), Ru(III), Mo(VI), Pd(II), Ba(II), La(III), and Y(III) contained in highly active liquid waste (HLW) towards DtOct/SiO₂-P was investigated at 323 K. The effects of contact time and the concentration of HNO₃ in a range of 0.1–5.0M on the adsorption of the tested metals were examined. The macroporous silica-based DtOct/SiO₂-P polymeric composite showed strong adsorption ability and high selectivity for Sr(II) over all of the tested metals except Ba(II). The optimum acidity of Sr(II) adsorption onto DtOct/SiO₂-P was determined to be 2.0M HNO₃. The bleeding behavior of DtOct/SiO₂-P in aqueous phase was evaluated using total organic carbon (TOC) analysis. The content of TOC increased with increasing the HNO₃ concentration and contact time. It resulted from the decrease in the stability of the associated species, C₈H₁₇-OH• DtBuCH18C6 formed through hydrogen binding, because of high temperature.     

Thermodynamics of complex formation in mixed solvents <Emphasis Type="Italic">K</Emphasis> and Δ<Emphasis Type="Italic">H</Emphasis> for the formation reaction of [Gly18C6] at 298.15 K

The influence of H₂O–EtOH and H₂O–Acetone mixed solvents at various compositions on the thermodynamics of complex formation reaction between crown ether 18-crown-6 (18C6) and glycine (Gly) was studied. The standard thermodynamic parameters of the complex [Gly18C6] (log K°, Δ_r H°, Δ_r S°) were calculated from thermochemical data at 298.15 K obtained by titration calorimetry. The complex stability and its formation enthalpy increase with increasing the non aqueous component concentration in both mixed solvents. The thermodynamic data were discussed on the basis of the solvation thermodynamic approach and the solvation contributions of the reagents and of the complex to the complex stability were analyzed.     

Different coordination modes of the dimethyldisulfide ligand in trimethylplatinum(IV) complexes

The reaction of [PtMe₃(bpy)(Me₂CO)](BF₄) (2) (prepared from [PtMe₃I(bpy)] (1) plus Ag(BF₄)) with MeSSMe resulted in the formation of [PtMe₃(bpy)(MeSSMe-κS)](BF₄) (3). A single-crystal X-ray diffraction analysis revealed in the octahedral Pt(IV) complex (configuration index: OC-6-33), a conformation of the monodentately κS bound MeSSMe ligand (C–S–S–C 92.7(4)°) being very close to that in non-coordinated MeSSMe, thus allowing some hyperconjugative interaction stabilizing the S–S bond. The reaction of [K(18C6)][(PtMe₃)₂(μ-I)(μ-pz)₂] (4; 18C6 = 18-crown-6, Hpz = pyrazole) with Ag(BF₄) and MeSSMe resulted in the formation of dinuclear complexes [(PtMe₃)₂(μ-pz)₂(μ-MeSSMe)] existing at room temperature in acetone solution as different fast interconverting isomers. At –40 °C, two isomers with a μ-1κS:2κS (5a) and a μ-1κS:2κS′ (5b) coordinated MeSSMe ligand in the ratio 2:1 could be identified ¹H NMR spectroscopically. DFT calculations of type 5 complexes revealed the existence of two conformers with a μ-MeSSMe-1κS:2κS ligand, which differ mainly in the C–S–S–C dihedral angle (66.4 vs. 180.0° 6a/6a′). They have essentially the same energy and a very low activation barrier in acetone as solvent (1.3 kcal/mol) for their mutual interconversion. A further equilibrium structure was identified to be an isomer having a μ-MeSSMe-1κS:2κS′ ligand (6b) that proved to be only 1.9 kcal/mol higher in energy than 6a/6a′.     

Syntheses,structures, and properties of two mononuclear cobalt(III) azido complexes containing a tetradentate N-donor Schiff base as end-capping ligand

Two hexacoordinated mononuclear Co(III) compounds of the type cis-[Co(L)(N₃)₂] X [1, X = ClO₄; 2, X = PF₆; L = N,N′-(bis(pyridine-2-yl)benzylidine)-1,4-butanediamine] have been synthesized and characterized by physicochemical and spectroscopic methods. The crystal structures of complexes 1 and 2 both have distorted octahedral geometry with two terminal azides in mutual cis orientations. In the crystalline state, two mononuclear units of 1 are associated by weak C–H…π interactions to produce a dimeric unit, which packs through C–H…O hydrogen bonds and π…π interactions leading to a 2-D continuum. The mononuclear units in 2 are engaged in weak cooperative intermolecular C–H…π interactions and multiple C–H…F hydrogen bonds giving rise to a 3-D network structure. These diamagnetic compounds are redox active and show luminescence in DMF solutions.     

Mesogenic and magnetic behavior in cobalt(II) and iron(II) compounds with long alkyl chains

Abstract  

Metal complexes with long alkyl chains [Co(C16-terpy)₃](BF₄)₂ (1), [Fe(C16-terpy)₂](BF₄)₂ (2), [Co(C16-terpy)₂](BPh₄)₂ (3), [Co(C14-terpy)₂](BF₄)₂ (4), and [Fe(C12C10C5-terpy)₂](BF₄)₂ (5) were synthesized and their physical properties characterized, where C16-terpy, C14-terpy, and C12C10C5-terpy are 4′-hexadecyloxy-2,2′:6′,2′′-terpyridine, 4′-tetradecyloxy-2,2′:6′,2′′-terpyridine, and 4′-5′′′-decyl-1′′′-heptadecyloxy-2,2′:6′,2″-terpyridine, respectively. Complexes 1, 2, and 5 exhibited liquid–crystal properties in the temperature ranges of 371–528 K and 466–556 K, and 88–523 K, respectively. Variable-temperature magnetic susceptibility measurements revealed that the Co(II) complexes 1 and 4 exhibited unique spin transitions (T _1/2↓ = 217 K and T _1/2↑ = 260 K for 1 and T _1/2↓ = 250 K and T _1/2↑ = 307 K for 4), so-called ‘reverse spin transition,’ induced by structural phase transitions. Complex 3 exhibited gradual spin-crossover behavior (T _1/2 = 160 K.), and complex 5 exhibited spin transitions (T _1/2↑ = 288 K and T _1/2↓ = 284 K) at the liquid crystal transition temperature. Compounds with multifunction, i.e., magnetic and liquid–crystal properties, are important in the development of molecular materials.     

Neutron activation analysis in forensic investigations: Trace elements characterization of cigarettes

A new type of silica-based chelating extraction resin, DtBuCH18C6/SiO₂-P, was prepared by impregnating a crown ether derivative, 4,4￠,(5￠)-di(tert-butylcyclohexano)-18-crown-6 (DtBuCH18C6), into the porous silica/polymer composite particles (SiO₂-P). The adsorption of Sr(II) and some other fission product elements was investigated by a batch adsorption experiment in HNO₃ This revised version was published online in July 2006 with corrections to the Cover Date.     

Kinetics of the adsorption of strontium(II) by a novel silica-based 4,4'',(5'')-di(tert-butylcyclohexano)-18-crown-6 extraction resin in nitric acid medium

A new type of silica-based chelating extraction resin, DtBuCH18C6/SiO₂-P, was prepared by impregnating a crown ether derivative, 4,4,(5)-di(tert-butylcyclohexano)-18-crown-6 (DtBuCH18C6), into the porous silica/polymer composite particles (SiO₂-P). The adsorption of Sr(II) and some other fission product elements was investigated by a batch adsorption experiment in HNO₃ medium. It was found that Sr(II) exhibits a strong adsorption onto the extraction resin, while the other fission product elements show almost no or only weak adsorption. The adsorption kinetics of Sr(II) was explained by assuming as the rate-controlling step the complex-formation reaction between Sr(II) and DtBuCH18C6 contained in the extraction resin. The rate equation of Sr(II) adsorption was determined as:-d[Sr(II)]/dt = k[Sr(II)][DtBuCH18C6][NO₃ ^–]^0.5.     

Chloro-free route to mixed-metal oxides. Synthesis of lead titanate nanoparticles from a single-source precursor route

A new heterobimetallic nitrilotriacetatoperoxotitanate complex of titanium and lead [Pb(H₂O)₃]₂[Ti₂(O₂)₂O(nta)₂]·4H₂O (C₆H₆O₆N=H₃nta) was isolated in pure crystals directly from the solution containing tetrabutyl orthotitanate, hydrogen peroxoide, lead acetate, and nitrilotriacetic acid at pH = 2.0–4.0. The isolated complex was characterized by elemental analyses, IR spectrum, thermal analysis (TG), and single-crystal X-ray diffraction. The single-crystal X-ray structural analysis revealed that the titanium atom is N,O,O′,O′′-chelated by the nitrilotriacetate and O,O′-chelated by the peroxo group and was coordinated to the bridging O atom in an overall pentagonal-bipyramidal geometry. The thermal decomposition of this precursor led to the formation of phase-pure lead titanate (PbTiO₃) at ≥450 °C. The morphology, microstructure, and crystalline of the resulting PbTiO₃ product have been characterized by BET, transmission electron microscopy, and powder X-ray diffraction. The TEM micrographs revealed that the size of the as-synthesized crystallines to be 50–100 nm range. The BET measurement revealed that the PbTiO₃ powders had a surface area of 5.6 m²/g.     

Synthesis and characterization of 2-phenylaniline cyclopalladated complexes

Reaction of the dinuclear complex [Pd{κ2-N2′,C1-2-(2′-NH₂C₆H₄)C₆H₄}Cl]₂ (1) with ligands (L = 4-picoline, sym-collidine) gave the six-membered palladacycles [Pd{κ2-N2′,C1-2-(2′-NH₂C₆H₄)C₆H₄}Cl(L)] (2). The complex 1 reacted with AgX (X = CF₃SO₃, BF₄) and bidentate ligands [L–L = phen (phenanthroline), dppe (bis(diphenylphosphino)ethane), bipy(2,2′-bipyridine) and dppp (bis(diphenylphosphino)propane)] giving the mononuclear orthopalladated complexes [Pd{κ2-N2′,C1-2-(2′-NH₂C₆H₄)C₆H₄}(L–L)] (3) [L–L = phen, dppe, bipy and dppp]. These compounds were characterized by physico-chemical methods, and the structure of [Pd{κ2-N2′,C1-2-(2′-NH₂C₆H₄)C₆H₄}Cl(L)] (L = sym-collidine) was determined by single-crystal X-ray analysis.     

Mesogenic and magnetic behavior in cobalt(II) and iron(II) compounds with long alkyl chains

Abstract  Metal complexes with long alkyl chains [Co(C16-terpy)₃](BF₄)₂ (1), [Fe(C16-terpy)₂](BF₄)₂ (2), [Co(C16-terpy)₂](BPh₄)₂ (3), [Co(C14-terpy)₂](BF₄)₂ (4), and [Fe(C12C10C5-terpy)₂](BF₄)₂ (5) were synthesized and their physical properties characterized, where C16-terpy, C14-terpy, and C12C10C5-terpy are 4′-hexadecyloxy-2,2′:6′,2′′-terpyridine, 4′-tetradecyloxy-2,2′:6′,2′′-terpyridine, and 4′-5′′′-decyl-1′′′-heptadecyloxy-2,2′:6′,2″-terpyridine, respectively. Complexes 1, 2, and 5 exhibited liquid–crystal properties in the temperature ranges of 371–528 K and 466–556 K, and 88–523 K, respectively. Variable-temperature magnetic susceptibility measurements revealed that the Co(II) complexes 1 and 4 exhibited unique spin transitions (T _1/2↓ = 217 K and T _1/2↑ = 260 K for 1 and T _1/2↓ = 250 K and T _1/2↑ = 307 K for 4), so-called ‘reverse spin transition,’ induced by structural phase transitions. Complex 3 exhibited gradual spin-crossover behavior (T _1/2 = 160 K.), and complex 5 exhibited spin transitions (T _1/2↑ = 288 K and T _1/2↓ = 284 K) at the liquid crystal transition temperature. Compounds with multifunction, i.e., magnetic and liquid–crystal properties, are important in the development of molecular materials. Graphical Abstract  

A two-dimensional ladder-type network in the 2:1 co-crystal of 1,2,5-thiadiazole-3,4-dicarboxylic acid and 4,4′-bipyridine

Abstract  

The crystal structure of the 2:1 co-crystal of 1,2,5-thiadiazole-3,4-dicarboxylic acid and 4,4′-bipyridine, (C₄H₂N₂O₄S)₂·C₁₀H₈N₂, has been determined by X-ray diffraction at the monoclinic space group C2/c with cell parameters of a = 21.388(7) ?, b = 6.735(2) ?, c = 14.877(5) ?, β = 110.431(3)°, and Z = 4. There are one molecule of thiadiazole and a half molecule of bipyridine in the asymmetric unit. The dihedral angle between the pyridine ring planes is 40.5(3)°. Two intramolecular O–H···N [2.730(7) ?] and O–H···O [2.433(6) ?] hydrogen bonds are observed in the thiadiazole molecule. In the crystal structure, the molecules form a unique two-dimensional ladder-type network linked by intermolecular O–H···N [2.704(4) ?] hydrogen bonds and S···O [3.100(5) ?] heteroatom interactions.     

Synthesis,structural and thermal characterization of metaphosphatecobalt(II) salt

A new inorganically template metaphosphate of Co(II) complex has been synthesized and characterized by different measurements such as DSC, FT-IR, C–H–N–O–S, ESR, TG-DTA and X-RD. Differential Scanning Calorimeter (DSC) elucidated negative specific heat of the system and has used to evaluate some thermo dynamical constants like activation energy (E _a), frequency factor (A), enthalpy and entropy of that system. The specific heat capacity of the system is measured both in atmospheric O₂ and N₂ atmosphere at different heating rates of 278, 283, 293 and 298 K min⁻¹ in room atmosphere and 288 K min⁻¹ in N₂ atmosphere.     

Crystallographic and theoretical studies of 4,4′-dimethyl-7,7′-bi([1,2,5]thiadiazolo[3,4-b]pyridylidene)–chloranilic acid (1/1) with intermolecular O–H···N hydrogen bonds and S···O heteroatom interactions

Abstract  The molecular and crystal structure of a 1:1 co-crystal of 4,4′-dimethyl-7,7′-bi([1,2,5]thiadiazolo[3,4-b]pyridylidene)–chloranilic acid, (1), has been determined by X-ray diffraction at the monoclinic space group P2₁/c with cell parameters of a = 8.422(6), b = 7.343(4), c = 16.112(7) ?, β = 104.988(8)°, V = 962.5(10) ?³ and Z = 2. In the crystal structure, two components connect via the intermolecular O–H···N hydrogen bonds [2.804(4) ?] and S···O heteroatom interaction [2.945(3) ?] with R ₂ ²(7) couplings to form a unique and infinite one-dimensional supramolecular tape structure. The calculations of (1) at the HF/6-31G(d), MP2/6-31G(d), and B3LYP/6-31G(d) levels can almost reproduce X-ray geometry. In addition, the distances of the intermolecular O–H···N and S···O interactions by MP2/6-31G(d) and B3LYP/6-31G(d) levels agree well with those in the crystal. The calculated binding energies corrected BSSE and ZPE are −4.487 (HF), −7.473 (MP2), and −5.640 (B3LYP) kcal/mol. The results suggest that the complex (1) is very stable and the dispersion interaction is significantly important for the attractive intermolecular interaction in (1). The NBO analysis has revealed that the n(N) → σ*(O–H) interaction gives the strongest stabilization to the system and the major interaction for the intermolecular S···O contact is n(O) → σ*(S–N). Index Abstract  In the crystal structure of the title compound, the molecules are linked by intermolecular O–H···N hydrogen bonds and short S···O heteroatom interactions with R ₂ ²(7) couplings to construct a unique and infinite one-dimensional supramolecular tape structure.      

Synthesis,properties and crystal structures of nitrobenzoatocopper(II) complexes with pyrazinecarboxamide

The synthesis, spectral characterization and crystal structures of two nitrobenzoatocopper(II) complexes, namely [Cu(2-O₂Nbz)₂(pca)₂(H₂O)₂] (1) and [Cu(3,5-(O₂N)₂bz)₂(pca)₂(H₂O)₂] (2) (where 2-O₂Nbz = 2-nitrobenzoate, 3,5-(O₂N)₂bz = 3,5-dinitrobenzoate, pca = pyrazinecarboxamide), are reported. Complexes 1 and 2 consist of centrosymmetric molecules with the Cu(II) atom monodentately coordinated by a pair of anionic 2-nitrobenzoato (1) or 3,5-dinitrobenzoato (2) ligands and a pair of pyrazinecarboxamide ligands, forming a nearly tetragonal basal plane, and by a pair of water ligands that complete the tetragonal–bipyramidal coordination polyhedron. The molecules of both complexes are linked by N–H⋯O and O–H⋯O hydrogen bonds and lie in planes, which have different orientations depending on the space group. Similar experiments with 3-nitrobenzoic acid resulted in the isolation of the hydrolysis product [Cu(pyzCOO)₂] _n (3) (pyzCOO = pyrazinecarboxylate). The known crystal structure of complex 3 has been re-determined at low temperature with significantly higher precision. The crystal packing and C–H⋯O/C–H⋯N hydrogen bonds are discussed.     

Synthesis,structures and magnetic properties of three metal-organic frameworks containing manganese(II)

Two new Mn(II) coordination polymers formed with molecular formula [Mn(H₂O)₂(HBTC)·(H₂O)] 1 and [Mn(H₂O)₂(4,4′bipy)(HBTC)₂]·(H4,4′bipy)₂ 2, where BTC = 1,2,4-benzenetricarboxylate and 4,4′bipy = 4,4′bipydine, have been synthesized via hydrothermal approach and characterized by single crystal X-ray diffraction techniques. 1 is composed of Mn–H₂O–Mn 1D chains and further the chains are linked by HBTC ligands to form a 2D network in the ab plane; 2 is constructed by Mn–4,4′bipy–Mn 1D chains along the b direction with Mn²⁺ ions coordinated to H₂BTC and water as terminal ligands to form a 2D network. We also prepared a third compound with the molecular formula of [Mn(H₂O)(HBTC)·(H₂O)] which has been recently structurally reported elsewhere. The magnetic properties of the three compounds have been studied in detail under variable temperatures.     

On the sol–gel preparation of different tungstates and molybdates

The preparation and characterization of the M′–M′′–O nitrate–tartrate (M′ = Ca, Ba, Gd and M′ = W, Mo) precursor gels synthesized by simple, inexpensive, and environmentally benign aqueous sol–gel method is reported. The obtained gels were studied by thermal (TG/DSC) analysis. TG/DSC measurements revealed the possible decomposition pathway of synthesized M′–M′′–O nitrate–tartrate gels. For the synthesis of different metal tungstates and molybdates, the precursor gels were calcined at different temperatures (650, 800, and 900 °C). According to the X-ray diffraction (XRD) analysis data, the crystalline compounds CaMo_1-x W _x O₄ doped with Ce³⁺ ions, BaMo_1-x W _x O₄ doped with Eu³⁺ ions and Gd₂Mo₃O₁₂ were obtained from nitrate–tartrate gels annealed at 650–900 °C temperatures. The XRD data confirmed that the fully crystalline single-phase powellite, scheelite, or Gd₂(MoO₄)₃ structures were formed already at 650 °C. Therefore, the suggested sol–gel method based on the complexation of metal ions with tartaric acid is suitable for the preparation of mixed tungstates–molybdates at relatively low temperature in comparison with solid-state synthesis.     

Polymorphism for a novel phosphoramidate; NMR and X-ray crystallography

Abstract  

New phosphoramidates with formula 3-NC₅H₄C(O)NHP(O)XY (X=Y=Cl (1), X=Y=NH–C(CH₃)₃ (2a,2b), X=Y=N(C₄H₉)₂ (3), X=Cl, Y=N(C₂H₅)₂ (4) were synthesized and characterized by IR, ¹H-, ¹³C-, ³¹P-NMR spectroscopy and CHN elemental analysis. Surprisingly, the reaction of compound 2a with LaCl₃, 7H₂O in 3:1 M ratio leads to a polymorph of this compound (2b). NMR spectra indicate that ² J(PNH_amide) in 2b (7.0 Hz) is very much greater than in 2a (4.1 Hz), while δ(³¹P) values are identical for both of them. In IR spectra, υ(P=O) is weaker but υ(C=O) is stronger in 2a than in 2b. The structures of 2a, 2b were determined by X-ray crystallography. These compounds form centrosymmetric dimers via two intermolecular P=O……H–N hydrogen bonds. Strong intermolecular N–H…N, N–H…O and weak C–H…O hydrogen bonds lead to a three-dimensional polymeric cluster in the 2a while intermolecular strong N–H……N and weak C–H……O hydrogen bonds form a two-dimensional polymeric chain in 2b.     

Crystal structural characterization of three chlorosalicylato titanocene compounds

Abstract  Three chlorosalicylato titanocene compounds, namely [(MeCp)₂Ti(O,O′)(OCC₆H₃-5-Cl)]₂ (1), [(MeCp)₂Ti(O,O′)(OCC₆H₂-3,5-Cl₂)] (2) and [(MeCp)₂Ti(O,O′)(OCC₆H-3,5,6-Cl₃)] (3) have been synthesized via the reaction of (MeCp)₂TiCl₂ [MeCp = η⁵-(CH₃)C₅H₄] with the corresponding substituted chlorosalicylic acids in aqueous-organic systems in high yields and characterized by elemental analysis, IR and ¹H NMR spectra. Single-crystal X-ray diffraction analysis shows that geometries at titanium (IV) atoms are distorted tetrahedrons and the exhibited frameworks are constructed through weak interactions, which are H-bonding, π–π stacking and C–H···π interactions. Additional weak interactions, such as Cl···Cl interactions in compound 1, are also present, which help to form and stabilize crystalline materials. It is noticeable that the discriminating framework structures of three compounds due to their weak interactions existing conspicuous changes which result from the number of chlorine atoms on substituted chlorosalicylates. Graphical Abstract  Three to four coordinated chlorosalicylato titanocene compounds, [(MeCp)₂Ti(O,O′)(OCC₆H₃-5-Cl)]₂ (1), [(MeCp)₂Ti(O,O′)(OCC₆H₂-3,5-Cl₂)] (2) and [(MeCp)₂Ti(O,O′)(OCC₆H-3,5,6-Cl₃)] (3) have been synthesized in aqueous-organic system in high yields. Single-crystal X-ray diffraction analysis shows that geometries at titanium (IV) atoms are distorted tetrahedrons and the exhibited frameworks are constructed through weak interactions. The number of chlorine atoms on substituted chlorosalicylates has an effect on their framework structures.      

Synthesis,crystal structures,and magnetic properties of two manganese(II) coordination polymers bearing 1,1′-biphenyl-3,3′-dicarboxylate ligands

Two Mn(II) coordination polymers, namely [Mn(bpda)] _n (1) and [Mn(bpda)(bpy)_0.5] _n (2) (H₂bpda = 1,1′-biphenyl-3,3′-dicarboxylic acid and bpy = 4,4′-bipyridine), have been synthesized from H₂bpdc, bpy, and MnSO₄·2H₂O under hydrothermal conditions. The complexes were characterized by physicochemical and spectroscopic methods, as well as by X-ray crystallography. Compound 1 possesses a 3D structure consisting of carboxylate-bridged edge-sharing Mn–O–Mn double chains. Compound 2 features a 3D open structure with a dinuclear Mn(II) secondary building unit. Magnetic susceptibility measurements of compounds 1 and 2 exhibit antiferromagnetic interactions between the nearest Mn(II), with J = –11.3 cm⁻¹ and g = 2.12 for 1, and J = –13.5 cm⁻¹ and g = 2.12 for 2.     

Young’s modulus calculations for cellulose I<Subscript>β</Subscript> by MM3 and quantum mechanics

Quantum mechanics (QM) and molecular mechanics (MM) calculations were performed to elucidate Young’s moduli for a series of cellulose I_β models. Computations using the second generation empirical force field MM3 with a disaccharide cellulose model, 1,4′-O-dimethyl-β-cellobioside (DMCB), and an analogue, 2,3,6,2′,3′,6′-hexadeoxy-1,4′-O-dimethyl-β-cellobioside (DODMCB), that cannot make hydrogen bonds reveal a considerable contribution of intramolecular hydrogen bonding to the molecular stiffness of cellulose I_β; the moduli for DMCB and DODMCB being 85.2 and 37.6 GPa, respectively. QM calculations confirm this contribution with modulus values of 99.7 GPa for DMCB and 33.0 GPa for DODMCB. However, modulus values for DMCB were considerably lower than values previously reported for cellulose I_β. MM calculations with extended cellulose chains (10–40 glucose units) resulted in modulus values, 126.0–147.5 GPa, more akin to the values reported for cellulose I_β. Comparison of the cellodecaose model, 1,4′-O-dimethyl-β-cellodecaoside (DMCD), modulus with that of its hydrogen bonding-deficient analogue, 2,3,6,2′,3′,6′-hexadeoxy-1,4′-O-dimethyl-β-cellodecaoside (DODMCD), corroborates the observed stiffness conferred by intramolecular hydrogen bonds; the moduli for DMCD and DODMCD being 126.0 and 63.3 GPa, respectively. Additional MM3 determinations revealed that modulus values were not strongly affected by intermolecular hydrogen bonding, with multiple strand models providing values similar to the single strand models; 87.5 GPa for a 7-strand DMCB model and 129.5 GPa for a 7 strand DMCD model.