Molecular Representations
Bar chart comparing CDDD virtual screening AUC against ECFP4, Mol2vec, Seq2seq FP, and VAE baselines

CDDD: Learning Descriptors by Translating SMILES

Winter et al. propose CDDD, a translation-based encoder-decoder that learns continuous molecular descriptors by translating between equivalent chemical representations like SMILES and InChI, pretrained on 72 million compounds.

Molecular Representations
Bar chart comparing SMILES and DeepSMILES error types, showing DeepSMILES eliminates parenthesis errors

DeepSMILES: Adapting SMILES Syntax for Machine Learning

DeepSMILES replaces paired parentheses and ring closure symbols in SMILES with a postfix notation and single ring-size digits, making it easier for generative models to produce syntactically valid molecular strings.

Molecular Representations
Bar chart comparing Group SELFIES vs SELFIES on MOSES benchmark metrics

Group SELFIES: Fragment-Based Molecular Strings

Group SELFIES extends SELFIES with group tokens representing functional groups and substructures, maintaining chemical robustness while improving distribution learning and molecular generation quality.

Molecular Representations
Bar chart showing MolBERT ablation: combining MLM, PhysChem, and SMILES equivalence tasks gives best improvement

MolBERT: Auxiliary Tasks for Molecular BERT Models

MolBERT pre-trains a BERT model on SMILES strings using masked language modeling, SMILES equivalence, and physicochemical property prediction as auxiliary tasks, achieving state-of-the-art results on virtual screening and QSAR benchmarks.

Molecular Representations
Bar chart comparing nach0 vs T5-base across molecular captioning, Q/A, reaction prediction, retrosynthesis, and generation

nach0: A Multimodal Chemical and NLP Foundation Model

nach0 unifies natural language and SMILES-based chemical tasks in a single encoder-decoder model, achieving competitive results across molecular property prediction, reaction prediction, molecular generation, and biomedical NLP benchmarks.

Molecular Representations
Encoder-decoder architecture diagram for translating chemical names between English and Chinese with performance comparison bar chart

Neural Machine Translation of Chemical Nomenclature

This paper applies character-level CNN and LSTM encoder-decoder networks to translate chemical names between English and Chinese, comparing them against an existing rule-based tool.

Molecular Representations
Bar chart showing randomized SMILES generate more of GDB-13 chemical space than canonical SMILES across training set sizes

Randomized SMILES Improve Molecular Generative Models

An extensive benchmark showing that training RNN generative models with randomized (non-canonical) SMILES strings yields more uniform, complete, and closed molecular output domains than canonical SMILES.

Molecular Representations
Diagram showing SMILES string flowing through encoder to fixed-length fingerprint vector and back through decoder

Seq2seq Fingerprint: Unsupervised Molecular Embedding

A GRU-based sequence-to-sequence model that learns fixed-length molecular fingerprints by translating SMILES strings to themselves, enabling unsupervised representation learning for drug discovery tasks.

Molecular Representations
Bar chart comparing SMI-TED ROC-AUC scores against ChemBERTa, ChemBERTa-2, MoLFormer, and GROVER on BBBP and HIV

SMI-TED: Encoder-Decoder Foundation Models for Chemistry

SMI-TED introduces encoder-decoder chemical foundation models (289M parameters) pre-trained on 91 million PubChem molecules, achieving strong results across property prediction, reaction yield, and molecule generation benchmarks.

Molecular Representations
Bar chart comparing binding affinity scores across SMILES, AIS, and SMI+AIS hybrid tokenization strategies

SMI+AIS: Hybridizing SMILES with Environment Tokens

Proposes SMI+AIS, a hybrid molecular representation combining standard SMILES tokens with chemical-environment-aware Atom-In-SMILES tokens, demonstrating improved molecular generation for drug design targets.

Molecular Representations
Diagram showing Transformer encoder-decoder architecture converting SMILES strings into molecular fingerprints

SMILES Transformer: Low-Data Molecular Fingerprints

A Transformer-based encoder-decoder pre-trained on 861K SMILES from ChEMBL24 produces 1024-dimensional molecular fingerprints that outperform ECFP and graph convolutions on 5 of 10 MoleculeNet tasks in low-data settings.

Molecular Representations
Bar chart comparing Atom Pair Encoding vs BPE tokenization on MoleculeNet classification tasks

SMILES vs SELFIES Tokenization for Chemical LMs

Introduces Atom Pair Encoding (APE), a chemistry-aware tokenizer for SMILES and SELFIES, and shows it consistently outperforms Byte Pair Encoding in RoBERTa-based molecular property classification on BBBP, HIV, and Tox21 benchmarks.