Supramolecular assembly of H‐bonded side‐chain polymers containing conjugated pyridyl H‐acceptor pendants and various low‐band‐gap H‐donor dyes bearing cyanoacrylic acid groups for organic solar cell applications

Novel supramolecular side‐chain polymers were constructed by complexation of proton acceptor (H‐acceptor) polymers, i.e., side‐chain conjugated polymers P1–P2 containing pyridyl pendants, with low‐band‐gap proton donor (H‐donor) dyes S1–S4 (bearing terminal cyanoacrylic acids) in a proper molar ratio. Besides unique mesomorphic properties confirmed by DSC and XRD results, the H‐bonds of supramolecular side‐chain structures formed by pyridyl H‐acceptors and cyanoacrylic acid H‐donors were also confirmed by FTIR measurements. H‐donor dyes S1–S4 in solid films exhibited broad absorption peaks located in the range of 471–490 nm with optical band‐gaps of 1.99–2.14 eV. Furthermore, H‐bonded polymer complexes P1/S1–P1/S4 and P2/S1–P2/S4 exhibited broad absorption peaks in the range of 440–462 nm with optical band‐gaps of 2.11–2.25 eV. Under 100 mW/cm² of AM 1.5 white‐light illumination, the bulk heterojunction polymer solar cell (PSC) devices containing an active layer of H‐bonded polymer complexes P1/S1–P1/S4 and P2/S1–P2/S4 (as electron donors) mixed with [6,6]‐phenyl C₆₁ butyric acid methyl ester (i.e., PCBM, as an electron acceptor) in the weight ratio of 1:1 were investigated. The PSC device containing H‐bonded polymer complex P1/S3 mixed with PCBM (1:1 w/w) gave the best preliminary result with an overall power conversion efficiency (PCE) of 0.50%, a short‐circuit current of 3.17 mA/cm², an open‐circuit voltage of 0.47 V, and a fill factor of 34%. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 5998–6013, 2009     

Si-H, P-H 和 S-H 键离解能Alfa取代基效应研究

CBS-Q and G3 methods were used to generate a large number of reliable Si--H, P---H and S--H bond dissociation energies （BDEs） for the first time. It was found that the Si--H BDE displayed dramatically different substituent effects compared with the C--H BDE. On the other hand, the P---H and S--H BDE exhibited patterns of substituent effects similar to those of the N--H and O--H BDE. Further analysis indicated that increasing the positive charge on Si of XSiH3 would strengthen the Si--H bond whereas increasing the positive charge on P and S of XPH2 and XSH would weaken the P---H and S--H bonds. Meanwhile, increasing the positive charge on Si of XSiH2^＋ stabilized the silyl radical whereas increasing the positive charge on P and S in XPH＂ and XS＊ destabilized P- and S-centered radicals. These behaviors could be reasonalized by the fact that Si is less electronegative than H while P and S are not. Finally, it was demonstrated that the spin-delocalization effect was valid for the Si-, P- and S-centered radicals.     

Anti‐Electrostatic Hydrogen Bonds

Ab initio and hybrid density functional techniques were employed to characterize a surprising new class of H‐bonded complexes between ions of like charge. Representative H‐bonded complexes of both anion–anion and cation–cation type exhibit appreciable kinetic stability and the characteristic theoretical, structural, and spectroscopic signatures of hydrogen bonding, despite the powerful opposition of Coulomb electrostatic forces. All such “anti‐electrostatic” H‐bond (AEHB) species confirm the dominance of resonance‐type covalency (“charge transfer”) interactions over the inessential (secondary or opposing) “ionic” or “dipole–dipole” forces that are often presumed to be essential for numerical modeling or conceptual explanation of the H‐bonding phenomenon.     

Density Functional Theory Study of Hydrogen Bonds of Bipyridine with 1,3,5-Benzenetricarboxylic Acid

The hydrogen‐bonded dimer and trimer formed between 1,3,5‐benzenetricarboxylic acid and bipyridine have been investigated using a density functional theory (DFT) method and 6‐31++G** basis set. The interaction energies are ?45.783 and ?89.998 kJ·mol^?1 for the most stable dimer and trimer, respectively, after the basis set superposition error and zero‐point corrections. The formation of O–H...N hydrogen bonds makes O–H symmetric stretching modes in the dimer and trimer red‐shifted relative to those of the 1,3,5‐benzenetricarboxylic acid monomer. The natural bond orbit analysis shows that the inter‐molecular charge transfers are 0.60475e and 1.20225e for the dimer and trimer, respectively. Thermodynamic analysis indicates that the formation of trimer is an exothermic and spontaneous process at low and room temperature. A supramolecule can be constructed through the strong N···H–O intermolecular hydrogen bonds between bipyridine and 1,3,5‐benzenetricarboxylic acid, which is in good agreement with the experimental results.     

Density functional study of indole–pyrrole heterodimer potential energy hypersurface

A density‐functional study of indole–pyrrole heterodimer potential energy hypersurface (PES) was performed. Eight stationary points were located on the B3LYP/6‐31++G(d,p) PES, three of which correspond to real minima, all of them being characterized with an N? H … π type hydrogen bonding. In two of these minima (the local ones), pyrrole subunit acts as a hydrogen bond proton donor, while the global minimum corresponds to indole–H … π(‐pyrrole) arrangement. Besides the interaction and dissociation energies corrected for BSSE and the monomer relaxation energies and the relevant structural parameters, anharmonic N? H and N? H … π vibrational frequencies were calculated for various N? H oscillators involved in this interaction from the 1‐D DFT vibrational potentials. On the basis of anharmonic vibrational frequency analysis, it was concluded that the two types of N? H … π hydrogen bonded dimers (indole vs. pyrrole being a proton donor) should be distinguishable with spectroscopic methods. Various contributions to the overall anharmonic frequency shifts upon hydrogen bonding were calculated and discussed as well. The charge field perturbation (CFP) technique was employed to study the electrostatic + polarization influence of the proton accepting unit on the N? H(… π) vibrational potential. The second‐order perturbation theory analysis (SOPT) of the Fock matrix (i.e., its Kohn–Sham analog) within the natural bond orbital (NBO) basis, as well as various NBO deletion analyses revealed an essentially one‐directional charge transfer (CT) of a π(C? C) → σ*(N? H) type in the case of all three minima. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2003     

A new phosphorothioic triamide structure: P(S)[NHCH2C6H5]3

The structure of N,N′,N′′‐tribenzylphosphorothioic triamide, C₂₁H₂₄N₃PS, (I), and analysis of the bond‐angle sums at the N atoms for this compound, and for 74 structures with a P(S)[N]₃ skeleton and the N atom in a three‐coordinate geometry found in the Cambridge Structural Database [CSD; Groom & Allen (2014). Angew. Chem. Int. Ed. 53 , 662–671], are reported. For (I), the bond‐angle sum at one of the N atoms [359 (1)°] shows a nearly planar configuration, while the other two show a nonplanar geometry with bond‐angle sums of 342 (1) and 347 (1)°. The location of the atoms attached to the nonplanar N atoms suggests an anti orientation of the corresponding lone electron pairs (LEPs) on these N atoms with respect to the P=S group. For 74 structures with a P(S)[N]₃ skeleton and with the N atom in a three‐coordinate geometry, the bond‐angle sums at the N atoms were found to be in the range 293–360°. Among 307 such three‐coordinate N atoms, 39% (120 N atoms) have bond‐angle sums in the range 359–360°, in accordance with sp² hybridization, and 45% (138 N atoms) have bond‐angle sums in the range 352–359°, with hybridization close to sp². For the orientation of the LEP with respect to the P=S group, the anti orientation was found to be a general rule for N atoms, with the corresponding bond‐angle sums deviating by more than 8° from the planar value of 360°. In the title structure, the S atom takes part in intermolecular (N—H...)(N—H...)S hydrogen bonds, connecting the molecules into extended chains parallel to the b axis. The co‐operation of one N atom in an N—H...S hydrogen bond as an H‐atom donor, and in an N—H...N hydrogen bond as an acceptor, is a novel feature of the crystal structure.     

A Theoretical Study on Hydrogen‐Bonded Complex of Proflavine Cation and Water: The Site‐dependent Feature of Hydrogen Bond Strengthening and Weakening

The intermolecular hydrogen‐bonds between proflavine cation (PC) and water molecules are investigated by density functional theory (DFT) and time‐dependent density functional theory (TDDFT) methods. The ground‐state geometry optimizations, electronic excitation energies and corresponding oscillation strengths of the low‐lying electronically excited states for the isolated proflavine cation, the hydrogen‐bonded PC–H2O dimer and PC–(H2O)2 trimer are calculated. Intermolecular hydrogen bonds at the central site of proflavine molecule are found to be stronger than the peripheral site. The hydrogen bond N–H???O for the hydrogen‐bonded dimer are indicated to be weakened in the excited states, since the excitation energy is increased slightly comparing to the monomer. Hydrogen bonds of PC–(H2O)2 trimer with the same type as the dimer are strengthened in the excited state, which is demonstrated by the decrease of the excited energies. Thus, hydrogen bond strengthening and weakening are observed to reveal site dependent feature in proflavine molecule. Furthermore, the hydrogen bond at central site induces the blue‐shift of the absorption spectrum, while the ones at peripheral site induce red‐shift. Hydrogen bonds with the same type at peripheral and central sites of proflavine molecule provide different effects on the photochemical and photophysical properties of proflavine.     

A new unconventional halogen bond C?X···H?M between HCCX (X = Cl and Br) and HMH (M = Be and Mg): An ab initio study

In this article, a new type of halogen‐bonded complex YCCX···HMY (X = Cl, Br; M = Be, Mg; Y = H, F, CH₃) has been predicted and characterized at the MP2/aug‐cc‐pVTZ level. We named it as halogen‐hydride halogen bonding. In each YCCX···HMY complex, a halogen bond is formed between the positively charged X atom and the negatively charged H atom. This new kind of halogen bond has similar characteristics to the conventional halogen bond, such as the elongation of the C? X bond and the red shift of the C? X stretch frequency upon complexation. The interaction strength of this type of halogen bond is in a range of 3.34–10.52 kJ/mol, which is smaller than that of dihydrogen bond and conventional halogen bond. The nature of the electrostatic interaction in this type of halogen bond has also been unveiled by means of the natural bond orbital, atoms in molecules, and energy decomposition analyses. © 2009 Wiley Periodicals, Inc. J Comput Chem 2010     

Density functional theory study of a molecular allosteric switch for 2,2′‐bipyridyl‐3,3′‐15‐crown‐5

A classical model of “molecular machine,” which acts as an ON–OFF switch for 2,2′‐bipyridyl‐3,3′‐15‐crown‐5 ( L ), has been theoretically studied. It is highly important to understand the mechanism of this switch. The alkali‐metal cations (Na⁺ and K⁺) and W(CO)₄ fragment are introduced to coordinate with the different active sites of L , respectively. The density functional theory (DFT) method is used for understanding the stereochemical structural natures and thermodynamic properties of all the target molecules at B3LYP/6‐31G(d) and SDD (Stuttgart–Dresden) level, together with the corresponding effective core potential (ECP) for tungsten (W). The fully optimized geometries have been performed with real frequencies, which indicate the minima states. The nucleophilicity of L has been investigated by the Fukui functions. The natural bond orbital analysis is used to study the intermolecular charge‐transfer interactions and explore the origin of the internal forces of the molecular switch. In addition, the binding energies, enthalpies, Gibbs free energies, and the cation exchange energies have been studied for L , W(CO)₄ L , and their corresponding complexes. The properties of the complexes displayed by in presence or absence of the W(CO)₄ fragment are also analyzed. The calculated results of allosterism displayed by L are in a good agreement with the experimental results. © 2010 Wiley Periodicals, Inc. J Comput Chem, 2011     

Polymeric dopant effects of bent‐core covalent‐bonded and hydrogen‐bonded structures on banana‐shaped liquid crystalline complexes

Two series of banana‐shaped liquid crystalline (LC) H‐bonded complexes HP_m / CB_n (i.e., bent‐core H‐bonded side‐chain homopolymer HP mixed with bent‐core covalent‐bonded small molecule CB ) and CP_m / HB_n (i.e., bent‐core covalent‐bonded side‐chain homopolymer CP mixed with bent‐core H‐bonded small molecular complex HB ) with various m/n molar ratios were developed. The bent‐core covalent‐ and H‐bonded structural moieties were homopolymerized in the banana‐shaped LC H‐bonded complexes HP_m / CB_n and CP_m / HB_n , respectively. The influences of m/n molar ratios (polymeric moieties vs. small molecular moieties) on the mesomorphic and electro‐optical properties of both banana‐shaped LC H‐bonded complexes HP_m / CB_n and CP_m / HB_n were investigated. The polar smectic phases could be achieved and stabilized by smaller contents of polymeric dopants in banana‐shaped LC H‐bonded complexes, such as HP1/CB10 , HP1/CB15 , CP1/HB10 , and CP1/HB15 , which possessed tunable spontaneous polarization (Ps) values according to the molar ratios of m/n , that is, lower Ps values obtained in H‐bonded complexes HP_m /CB_n and CP_m / HB_n with higher ratios of H‐bonded moieties (larger m/n molar ratios), respectively. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 764–774, 2010     

A comparative study of some lithium and hydrogen‐bonded complexes: Ab initio and QTAIM studies

The nature of the interactions of cyanide with lithium and hydrogen halides was investigated using ab initio calculations and topological analysis of electron density. The computed properties of the lithium‐bonded complexes RCN···LiX (R = H, F, Cl, Br, C?CH, CH?CH₂, CH₃, C₂H₅; X = Cl, Br) were compared with those of corresponding hydrogen‐bonded complexes RCN···HX. The results show that both types of intermolecular interactions are “closed‐shell” noncovalent interactions. The effect of substitution on the interaction energy and electron density at the bond critical points of the lithium and hydrogen bonding interactions is similar. In comparison, the interaction energies of lithium‐bonded complexes are more negative than those of hydrogen‐bonded counterparts. The electrostatic interaction plays a more important role in the lithium bond than in the hydrogen bond. On complex formation, the net charge and energy of the Li atom decrease and the atomic volume increases, while the net charge and energy of the H atom increase and the atomic volume decreases. © 2013 Wiley Periodicals, Inc.     

A novel tubular hydrogen‐bond pattern in a new diazaphosphole oxide: a combination of X‐ray crystallography and theoretical study of hydrogen bonds

In the structure of 2‐(4‐chloroanilino)‐1,3,2λ⁴‐diazaphosphol‐2‐one, C₁₂H₁₁ClN₃OP, each molecule is connected with four neighbouring molecules through (N—H)₂…O hydrogen bonds. These hydrogen bonds form a tubular arrangement along the [001] direction built from R ³₃(12) and R ₄³(14) hydrogen‐bond ring motifs, combined with a C (4) chain motif. The hole constructed in the tubular architecture includes a 12‐atom arrangement (three P, three N, three O and three H atoms) belonging to three adjacent molecules hydrogen bonded to each other. One of the N—H groups of the diazaphosphole ring, not co‐operating in classical hydrogen bonding, takes part in an N—H…π interaction. This interaction occurs within the tubular array and does not change the dimension of the hydrogen‐bond pattern. The energies of the N—H…O and N—H…π hydrogen bonds were studied by NBO (natural bond orbital) analysis, using the experimental hydrogen‐bonded cluster of molecules as the input file for the chemical calculations. In the ¹H NMR experiment, the nitrogen‐bound proton of the diazaphosphole ring has a high value of 17.2 Hz for the ²J _H–P coupling constant.     

Intramolecular hydrogen bonding in structural conformers of 2‐amino methylene malonaldehyde: AIM and NBO studies

The molecular structure and intramolecular hydrogen bond energies of 44 conformers of 2‐Amino methylene malonaldehyde were investigated at MP2 and B3LYP levels of theory using the standard 6‐311++G** basis set and AIM and NBO analysis. The calculated geometrical parameters and conformational analysis in gas phase show that the closed ring via intramolecular hydrogen bonded conformers of this compound are more stable than the other ones. Hydrogen bond energies for H‐bonded conformers were obtained from the related rotamers method (RRM) and Schuster method, and also the nature of H‐bonding of them has been investigated by means of the Bader theory of atoms in molecules, which is based on topological properties of the electron density. Delocalization effects can be identified from the presence of off diagonal elements of the Fock matrix in the NBO basis. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2010     

Influence of Intermolecular N?H⋅⋅⋅π Interactions on Molecular Packing and Field‐Effect Performance of Organic Semiconductors

Charge transport in organic semiconductors is strongly dependent on their molecular packing modes in the solid state. Therefore, understanding the relationship between molecular packing and charge transport is imperative, both experimentally and theoretically. However, so far, the fundamental effects of solid‐state packing and molecular interactions (e.g. N? H ??? π) on charge transport need further elucidation. Herein, indolo[3,2‐b]carbazole (ICZ) and a derivative thereof are used as examples to approach this scientific target. An interesting insight obtained thereby is that N? H ??? π interactions among ICZ molecules facilitate charge transport for higher mobility. Subtle changes in the of N? H ??? π interactions can significantly influence both the molecular packing and the charge‐transport properties. Therefore, a method for exploiting intermolecular N? H ??? π interactions would yield novel molecular systems with designable characteristics.     

Guest⊂Guest⊂Host Multicomponent Molecular Crystals: Entrapment of Guest⊂Guest in Honeycomb Networks Formed by Self‐Assembly of 1,3,5‐Tri(4‐hydroxyaryl)benzenes

Sterically‐engineered rigid trigonal molecular modules based on 1,3,5‐tri(4‐hydroxyphenyl)benzenes H1 and H2 undergo O‐H???O hydrogen‐bonded self‐assembly into eight‐fold catenated hexagonal (6,3) and two‐fold interpenetrated undulated square (4,4) networks, respectively. In the presence of [18]crown‐6 as a guest, the triphenol H1 is found to self‐assemble into a honeycomb network with hexagonal voids created between three triphenol building blocks. The guest [18]crown‐6 molecules are found to be nicely nested in hexagonal enclosures. The empty spaces within the crowns can be further filled with neutral (MeOH/water, MeOH/MeNO₂) or ionic guest species such as KI/KAcAc to furnish novel multicomponent assemblies, that is, guest ? guest ? host, that typify Russian dolls. In contrast, triphenol H2 is found to yield analogous multicomponent molecular crystals in which the guest crown–K⁺ acts as a spacers in the hydrogen‐bonded self‐assembly that leads to distorted chicken wire networks.     

Modulation of a Molecular π‐Electron System in a Purely Organic Conductor that Shows Hydrogen‐Bond‐Dynamics‐Based Switching of Conductivity and Magnetism

New important aspects of the hydrogen‐bond (H‐bond)‐dynamics‐based switching of electrical conductivity and magnetism in an H‐bonded, purely organic conductor crystal have been discovered by modulating its tetrathiafulvalene (TTF)‐based molecular π‐electron system by means of partial sulfur/selenium substitution. The prepared selenium analogue also showed a similar type of phase transition, induced by H‐bonded deuterium transfer followed by electron transfer between the H‐bonded TTF skeletons, and the resulting switching of the physical properties; however, subtle but critical differences due to sulfur/selenium substitution were detected in the electronic structure, phase transition nature, and switching function. A molecular‐level discussion based on the crystal structures shows that this chemical modification of the TTF skeleton influences not only its own π‐electronic structure and π–π interactions within the conducting layer, but also the H‐bond dynamics between the TTF π skeletons in the neighboring layers, which enables modulation of the interplay between the H‐bond and π electrons to cause such differences.     

A Novel Organosulfonate Cadmium(II) Complex with Graphite‐like 2D Layer Linked by Hydrogen Bonds

A novel mixed‐ligand complex, [Cd(im)₆][Cd(im)₃(H₂O)₃]₂(ans)₆ · 8H₂O ( 1 ), was obtained from the reaction ofCd(OAc)₂ · 2H₂O, imidazole (im) and sodium 4‐aminonaphthalene‐1‐sulfonate tetrahydrate (Na‐ans) in a mixed solvent at 25 °C. The complex was characterized by elemental analysis, IR spectroscopy, and X‐ray single crystal diffraction. There are two kinds of cations constructed by Cd^II atoms with a octahedral coordination arrangement in 1 . The Cd^II atom is bonded by six nitrogen atoms from six im ligands in the first cation, and the second central Cd^II atom is bonded by three nitrogen atoms of im molecules and three oxygen atoms belonging to water molecules. The ans anion acts as a counterion to balance the charge, and the adjacent anions are reversed but non‐parallel interlinked by N–H ··· O(S) hydrogen bonds into graphite‐like 2D sheet viewed from the c axis. The anionic channels along the [110] direction are filled with the cations, and the two kinds of cations are alternatingly arranged in the channels. The hydrogen‐bonding interactions together with the ionic bonds stabilize the crystal structure. The thermostability of the complex was investigated by TG and DSC.     

A polarizable dipole–dipole interaction model for evaluation of the interaction energies for NH···OC and CH···OC hydrogen‐bonded complexes

In this article, a polarizable dipole–dipole interaction model is established to estimate the equilibrium hydrogen bond distances and the interaction energies for hydrogen‐bonded complexes containing peptide amides and nucleic acid bases. We regard the chemical bonds N? H, C?O, and C? H as bond dipoles. The magnitude of the bond dipole moment varies according to its environment. We apply this polarizable dipole–dipole interaction model to a series of hydrogen‐bonded complexes containing the N? H···O?C and C? H···O?C hydrogen bonds, such as simple amide‐amide dimers, base‐base dimers, peptide‐base dimers, and β‐sheet models. We find that a simple two‐term function, only containing the permanent dipole–dipole interactions and the van der Waals interactions, can produce the equilibrium hydrogen bond distances compared favorably with those produced by the MP2/6‐31G(d) method, whereas the high‐quality counterpoise‐corrected (CP‐corrected) MP2/aug‐cc‐pVTZ interaction energies for the hydrogen‐bonded complexes can be well‐reproduced by a four‐term function which involves the permanent dipole–dipole interactions, the van der Waals interactions, the polarization contributions, and a corrected term. Based on the calculation results obtained from this polarizable dipole–dipole interaction model, the natures of the hydrogen bonding interactions in these hydrogen‐bonded complexes are further discussed. © 2013 Wiley Periodicals, Inc.     

A strategy for synthesis of ion‐bonded amphiphilic miktoarm star copolymers via supramolecular macro‐RAFT agent

Amphiphilic supramolecular miktoarm star copolymers linked by ionic bonds with controlled molecular weight and low polydispersity have been successfully synthesized via reversible addition‐fragmentation chain transfer (RAFT) polymerization using an ion‐bonded macromolecular RAFT agent (macro‐RAFT agent). Firstly, a new tetrafunctional initiator, dimethyl 4,6‐bis(bromomethyl)‐isophthalate, was synthesized and used as an initiator for atom transfer radical polymerization (ATRP) of styrene to form polystyrene (PSt) containing two ester groups at the middle of polymer chain. Then, the ester groups were converted into tertiary amino groups and the ion‐bonded supramolecular macro‐RAFT agent was obtained through the interaction between the tertiary amino group and 2‐dodecylsulfanylthiocarbonylsulfanyl‐2‐methyl propionic acid (DMP). Finally, ion‐bonded amphiphilic miktoarm star copolymer, (PSt)₂‐poly(N‐isopropyl‐acrylamide)₂, was prepared by RAFT polymerization of N‐isopropylacrylamide (NIPAM) in the presence of the supramolecular macro‐RAFT agent. The polymerization kinetics was investigated and the molecular weight and the architecture of the resulting star polymers were characterized by means of ¹H‐NMR, FTIR, and GPC techniques. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 5805–5815, 2008     

Study of supramolecular side‐chain and cross‐linking polymers by complexation of various H‐donor acids with H‐acceptor copolymers containing pendent carbazole and fluorescent pyridyl units

Two H‐bonded acceptor (H‐acceptor) homopolymers 14 and 17 were successfully prepared by polymerization of fluorescent pyridyl monomers PBT and PBOT ( 12 and 13 ), which were synthesized via Sonogashira coupling and Wittig‐Horner reactions. To increase the glass transition temperatures as well as reduce the π‐π stacking of the photoluminescent (PL) H‐acceptor copolymers and their H‐bonded polymer complexes, fluorescent monomers 12 and 13 were copolymerized with N‐vinylcarbazole monomer CAZ (23) to produce H‐acceptor copolymers 15–16 and 18–19 . Supramolecular side‐chain and crosslinking polymers (i.e., H‐bonded polymer complexes) obtained by complexation of light‐emitting H‐acceptor polymers 14–19 with various proton donor (H‐donor) acids 20–22 were further characterized by DSC, POM, FTIR, XRD, and PL measurements. The mesomorphic properties can be tuned from the nematic phase in H‐acceptor homopolymers ( 14 and 17 ) to the tilted smectic C phase in their H‐bonded polymer complexes ( 14/20–21 and 17/20–22 ) by the introduction of H‐donor acids (20–22). Moreover, the PL properties of light‐emitting H‐acceptor polymers can be adjusted not only by the central structures of the conjugated pyridyl cores but also by their surrounding nonfluorescent H‐donor acids. In general, redder shifts of PL emissions in H‐bonded polymer complexes occurred when the light‐emitting H‐acceptor polymers were complexed with H‐donors having smaller pKa values. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 2734–2753, 2009